Passive amplification of signals

• US 20080001659A1
• Filed: 02/16/2007
• Published: 01/03/2008
• Est. Priority Date: 06/30/2006
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Nokia Corporation
• Inventors: Vaisanen, Risto
• Granted Patent: US 7,844,233 B2
• Time in Patent Office: Days
• US Class Current: 330/7
• CPC Class Codes: H03D 2200/0025 Gain control circuits
• CPC Class Codes: H03D 7/1441 using field-effect transistors H03D7/145 takes precedence
• CPC Class Codes: H03D 7/1458 Double balanced arrangements, i.e. where both input signals are differential
• CPC Class Codes: H03D 7/1466 Passive mixer arrangements
• CPC Class Codes: H03D 7/1483 comprising components for selecting a particular frequency component of the output
• CPC Class Codes: H03F 1/0205 in transistor amplifiers
• CPC Class Codes: H03F 2200/252 Multiple switches coupled in the input circuit of an amplifier are controlled by a circuit, e.g. feedback circuitry being controlling the switch
• CPC Class Codes: H03F 2200/336 A I/Q, i.e. phase quadrature, modulator or demodulator being used in an amplifying circuit
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2203/45551 the IC comprising one or more switched capacitors
• CPC Class Codes: H03F 2203/45631 the LC comprising one or more capacitors, e.g. coupling capacitors
• CPC Class Codes: H03F 3/005 using switched capacitors, e.g. dynamic amplifiers; using switched capacitors as resistors in differential amplifiers H03F3/45 takes precedence
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H03F 3/45 Differential amplifiers differential sense amplifiers G11C7/062
• CPC Class Codes: H03G 1/0088 using discontinuously variable devices, e.g. switch-operated

Abstract

A passive amplifier structure capable of multiplying the voltage of an input signal is provided. In a first stage, a first and a second capacitance are connected between a first and a second input port of a balanced input port in response to a first oscillator signal. In a second stage, in response to a second oscillator signal having a phase different from that of the first oscillator signal, the first capacitance is connected between the first input port and a third capacitance and the second capacitance is connected between the second input port and the third capacitance. An output voltage over the third capacitance is obtained from terminals of the third capacitance. Presented embodiments also describe an automatic gain control feature.

Claims

1. A method, comprising:

receiving an input signal voltage into a first input port and a second input port of a balanced input port;

connecting, in a first stage, in response to a first oscillator signal, a first capacitance and a second capacitance between the first input port and the second input port of the balanced input port;

connecting, in a second stage, in response to a second oscillator signal, the first capacitance between the first input port and a third capacitance, and the second capacitance between the second input port and the third capacitance; and

obtaining a voltage over the third capacitance as an output voltage.

2. The method of claim 1, further comprising:

connecting a first terminal of the first capacitance, connected to the second input port in the first stage, to the first input port at the second stage;

connecting a second terminal of the first capacitance to a first terminal of the third capacitance in the second stage;

connecting a first terminal of the second capacitance, connected to the first input port in the first stage, to the second input port in the second stage; and

connecting a second terminal of the second capacitance to a second terminal of the third capacitance in the second stage.

3. The method of claim 1, further comprising:

charging, in the first stage, the first capacitance and the second capacitance with a voltage corresponding to the voltage over the first input port and the second input port; and

releasing, in the second stage, the charge in the first capacitance and the second capacitance into the third capacitance in series with the current voltage over the first input port and the second input port, to produce a voltage over the third capacitance, which is the sum of the voltage over the first capacitance in the first stage, the voltage over the second capacitance in the first stage, and the current voltage over the first input port and the second input port.

4. The method of claim 1, further comprising:

producing the first oscillator signal and the second oscillator signal from a local oscillator signal used for downmixing a received radio signal.

5. The method of claim 1, further comprising:

connecting, in the first stage, the first capacitance and the second capacitance between the first input port and the second input port either in series or in parallel depending on a desired voltage multiplication factor of the output signal.

6. The method of claim 5, further comprising:

connecting, in the first stage, the first capacitance and the second capacitance between the first input port and the second input port in series when the desired voltage multiplication factor is two and in parallel when the desired voltage multiplication factor is three.

7. The method of claim 5, further comprising:

connecting the first terminal and the second terminal of the first capacitance to the first input port in the first stage; and

connecting the first terminal and the second terminal of the second capacitance to the second input port in the first stage when the desired voltage multiplication factor is one.

8. The method of claim 5, further comprising:

connecting, in the first stage, the first capacitance and the second capacitance in series between the first input port and the second input port; and

providing, in series with the first and the second capacitance, an additional capacitance having a capacitance value determined according to the desired voltage multiplication factor.

9. The method of claim 1, further comprising:

configuring the frequencies of the first oscillator signal and the second oscillator signal to be higher than the highest frequency component of input signals at the input ports.

10. The method of claim 1, further comprising:

defining a corner frequency of a low-pass filter with the capacitance values of the first capacitance, the second capacitance, and the third capacitance; and

low-pass filtering an input signal input to the first and the second input port.

11. The method of claim 1, further comprising:

connecting, in the first stage, the first capacitance and the second capacitance between the first input port and the second input port in series; and

providing a fourth capacitance in series between the first capacitance and the second capacitance in the first stage,

wherein the capacitance value of the fourth capacitance is adjustable to enable adjustable voltage multiplication.

12. The method of claim 1, further comprising:

connecting, in the first stage, the first capacitance and the second capacitance between the first input port and the second input port in series;

providing a fourth capacitance in series with the first capacitance in the first stage; and

providing a fifth capacitance in series with the second capacitance in the first stage,

wherein the capacitance values of the fourth capacitance and the fifth capacitance are adjustable to enable adjustable voltage multiplication.

13. The method of claim 1, further comprising:

configuring the first stage to be the first half cycle of the oscillator signals; and

configuring the second stage to be the second half cycle of the oscillator signals.

14. The method of claim 1, further comprising:

configuring the first oscillator signal and the second oscillator signal to be a same oscillator signal.

15. The method of claim 1, further comprising:

configuring the first oscillator signal and the second oscillator signal to have a same frequency and different phases.

16. A method, comprising:

producing a first oscillator signal and a second oscillator signal having the same frequency;

charging a first capacitance and a second capacitance with an input signal sample received into a first input port and a second input port of a balanced input port during a first half cycle of the first oscillator signal and the second oscillator signal; and

charging a third capacitance operationally coupled with the first capacitance and the second capacitance, with the charges in the first capacitance and the second capacitance together with an input signal sample received into the first input port and the second input port of the balanced input port during a second half cycle of the first oscillator signal and the second oscillator signal.

17. An apparatus, comprising:

an input interface comprising a balanced input port configured to receive a balanced input signal and an oscillator signal input port configured to receive a first oscillator signal and a second oscillator signal;

a first capacitance;

a second capacitance;

a third capacitance;

a first set of switches responsive to the first oscillator signal and configured to connect, in response to the first oscillator signal, the first and the second capacitance between a first input port and a second input port of the balanced input port;

a second set of switches responsive to the second oscillator signal and configured to connect, in response to the second oscillator signal, the first capacitance between the first input port and the third capacitance, and the second capacitance between the second input port and the third capacitance; and

an output port connected to terminals of the third capacitance.

18. The apparatus of claim 17, wherein a first set of switches is configured to connect, when closed, a first terminal of the first and the second capacitance to the first input port and a second terminal of the first and the second capacitance to the second input port, and the second set of switches is configured to connect, when closed, the first terminal of the first capacitance to a first terminal of the third capacitance, the second terminal of the first capacitance to the first input port, the first terminal of the second capacitance to the second input port, and the second terminal of the second capacitance to a second terminal of the third capacitance.

19. The apparatus of claim 17, wherein the first oscillator signal and the second oscillator signal are a same oscillator signal.

20. The apparatus of claim 17, wherein the first oscillator signal and the second oscillator signal have a same frequency and different phases.

21. The apparatus of claim 17, further comprising:

a local oscillator signal generator configured to apply the first oscillator signal and the second oscillator signal to the oscillator input port.

22. The apparatus of claim 21, wherein the local oscillator signal generator is configured to produce the first oscillator signal and the second oscillator signal from a local oscillator signal used for downmixing a received radio signal.

23. The apparatus of claim 21, wherein the local oscillator signal generator is configured to produce the first oscillator signal and the second oscillator signal to have a frequency higher than the highest expected frequency component of input signals at the input ports.

24. The apparatus of claim 17, further comprising:

a controllable switching mechanism configured to connect, when the first set of switches is closed, the first capacitance and the second capacitance between the first input port and the second input port either in series or in parallel depending on a desired voltage multiplication factor effected by the apparatus on an input signal input to the balanced input port.

25. The apparatus of claim 24, wherein the switching mechanism is configured to connect the first capacitance and the second capacitance between the first input port and the second input port in series when the desired voltage multiplication factor is two and in parallel when the desired voltage multiplication factor is three.

26. The apparatus of claim 24, wherein the switching mechanism is further configured to connect, when the first set of switches is closed, two terminals of the first capacitance to the first input port and two terminals of the second capacitance to the second input port when the desired voltage multiplication factor is one.

27. The apparatus of claim 24, further comprising:

an additional capacitance having a capacitance value determined according to the desired voltage multiplication factor,

wherein the switching mechanism is configured to connect the first capacitance and the second capacitance in series with the additional capacitance between the first input port and the second input port.

28. The apparatus of claim 17, wherein the apparatus is configured to function as a low-pass filter having a corner frequency defined by a ratio of the capacitance values of the first capacitance, the second capacitance, and the third capacitance.

29. The apparatus of claim 17, wherein

the first set of switches comprises a first switch connected between the first input port and a first terminal of the first capacitance, a second switch connected between the second input port and a second terminal of the first capacitance, a third switch connected between the first input port and a first terminal of the second capacitance, and a fourth switch connected between the second input port and a second terminal of the second capacitance, and

the second set of switches comprises a fifth switch connected between the first terminal of the first capacitance and a first terminal of the third capacitance, a sixth switch connected between the first input port and the second terminal of the first capacitance, a seventh switch connected between the second input port and the first terminal of the second capacitance, and an eighth switch connected between the second terminal of the second capacitance and a second terminal of the third capacitance.

30. The apparatus of claim 17, further comprising:

a fourth capacitance,

wherein the first set of switches is configured to connect, when closed, the fourth capacitance together with the first capacitance and the second capacitance in series between the first input port and the second input port of the balanced input port.

31. The apparatus of claim 30, further comprising:

an adjustment circuit configured to adjust the capacitance value of the fourth capacitance and to control a voltage multiplication factor of the apparatus.

32. The apparatus of claim 17, further comprising:

a fifth capacitance; and

a sixth capacitance,

wherein the first set of switches is configured to connect, when closed, the fifth capacitance in series with the first capacitance, the sixth capacitance in series with the second capacitance, and the first capacitance and the fifth capacitance in parallel with the second capacitance and the sixth capacitance between the first input port and the second input port of the balanced input port.

33. The apparatus of claim 32, further comprising:

an adjustment circuit configured to adjust the capacitance value of the fifth capacitance and the sixth capacitance and to control a voltage multiplication factor of the apparatus.

34. An automatic gain control amplifier, comprising:

an input interface comprising a balanced input port configured to receive a balanced input signal and an oscillator signal input port configured to receive a first oscillator signal and a second oscillator signal;

a first capacitance;

a second capacitance;

a third capacitance;

a first set of switches responsive to the first oscillator signal and configured to connect, in response to the first oscillator signal, the first and the second capacitance between a first input port and a second input port of the balanced input port;

a second set of switches responsive to the second oscillator signal and configured to connect, in response to the second oscillator signal, the first capacitance between the first input port and the third capacitance, and the second capacitance between the second input port and the third capacitance; and

an output port connected to terminals of the third capacitance.

35. A radio transmitter comprising an amplifier, comprising:

an input interface comprising a balanced input port configured to receive a balanced input signal and an oscillator signal input port configured to receive a first oscillator signal and a second oscillator signal;

a first capacitance;

a second capacitance;

a third capacitance;

a first set of switches responsive to the first oscillator signal and configured to connect, in response to the first oscillator signal, the first and the second capacitance between a first input port and a second input port of the balanced input port;

a second set of switches responsive to the second oscillator signal and configured to connect, in response to the second oscillator signal, the first capacitance between the first input port and the third capacitance, and the second capacitance between the second input port and the third capacitance; and

an output port connected to terminals of the third capacitance.

36. An apparatus, comprising:

input means comprising a balanced input port for receiving a balanced input signal and an oscillator signal input port for receiving a first and a second oscillator signal;

first capacitance means for holding charge;

second capacitance means for holding charge;

third capacitance means for holding charge;

first switching means responsive to the first oscillator signal for connecting, in response to the first oscillator signal, the first capacitance means and the second capacitance means between a first input port and a second input port of the balanced input port;

second switching means responsive to the second oscillator signal for connecting, in response to the second oscillator signal, the first capacitance means between the first input port and the third capacitance means and the second capacitance means between the second input port and the third capacitance means; and

output means connected to terminals of the third capacitance means.