Direct Coupled Biasing Circuit for High Frequency Applications

• US 20120319673A1
• Filed: 06/17/2011
• Published: 12/20/2012
• Est. Priority Date: 06/17/2011
• Status: Active Grant

• Current Assignee: Tensorcom Inc
• Original Assignee: Tensorcom Inc
• Inventors: Soe, Zaw, Tham, KhongMeng
• Granted Patent: US 9,143,204 B2
• Time in Patent Office: Days
• US Class Current: 323/312
• CPC Class Codes: G05F 3/16 being semiconductor devices
• CPC Class Codes: H01Q 1/50 Structural association of antennas with earthing switches, lead-in devices or lightning protectors
• CPC Class Codes: H03F 1/30 Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters in differential amplifiers H03F3/45479
• CPC Class Codes: H03F 2200/555 A voltage generating circuit being realised for biasing different circuit elements
• CPC Class Codes: H03F 3/193 with field-effect devices H03F3/195 takes precedence
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H03K 17/56 by the use, as active elements, of semiconductor devices using diodes H03K17/74
• CPC Class Codes: H03K 3/012 Modifications of generator to improve response time or to decrease power consumption
• CPC Class Codes: H04B 5/24 Inductive coupling

Abstract

This invention eliminates the need for “capacitor coupling” or “transformer coupling,” and the associated undesirable parasitic capacitance and inductance associated with these coupling techniques when designing high frequency (˜60 GHz) circuits. At this frequency, the distance between two adjacent stages needs to be minimized. A resonant circuit in series with the power or ground leads is used to isolate a biasing signal from a high frequency signal. The introduction of this resonant circuit allows a first stage to be “directly coupled” to a next stage using a metallic trace. The “direct coupling” technique passes both the high frequency signal and the biasing voltage to the next stage. The “direct coupling” approach overcomes the large die area usage when compared to either the “AC coupling” or “transformer coupling” approach since neither capacitors nor transformers are required to transfer the high frequency signals between stages.

Claims

1. An apparatus comprising:

a second transistor scaled to a first transistor by a value;

a first current through the first transistor generates a first biasing voltage;

a control loop monitors the first biasing voltage and generates a second biasing voltage; and

a first resonant parallel LC load directly couples the second biasing voltage to an input of the second transistor to control a second current through the second transistor, whereby

the second current is scaled to the first current by the value.

2. The apparatus of claim 1, whereby the first transistor is connected in saturation.

3. The apparatus of claim 2, whereby the second biasing voltage is substantially equal to the first biasing voltage.

4. The apparatus of claim 3, further comprising:

an output of a third transistor directly coupled to the first resonant parallel LC load;

a second resonant parallel LC load directly couples a power supply to an output of the second transistor;

an input signal coupled to the input of the second transistor that generates an intermediate signal at the output of the second transistor; and

the intermediate signal directly coupled to an input of the third transistor.

5. The apparatus of claim 4, whereby

the LC loads comprise parasitic and non-parasitic capacitance and inductance components, and parasitic resistance.

6. The apparatus of claim 4, whereby

the intermediate signal combines with the second biasing voltage at the output of the third transistor and is directly coupled to the input of the second transistor to generate an output signal at the output of the second transistor.

7. The apparatus of claim 6, whereby

the LC loads resonate at a frequency to select a frequency band within an allotted spectrum.

8. The apparatus of claim 1, whereby

the first current is adjustable, a width of the first transistor is adjustable or both are adjustable.

9. An apparatus comprising:

an adjustable biasing voltage coupled through a first resonant parallel LC load of a first stage to an output of the first stage;

the output of the first stage is directly coupled to an input of a next stage; and

at least one characteristic of the next stage is controlled by the adjustable biasing voltage.

10. The apparatus of claim 9, further comprising:

a first transistor that generates the adjustable biasing voltage; and

a second transistor in the next stage, whereby the first transistor is a scaled version of the second transistor.

11. The apparatus of claim 10, whereby

the characteristic is a current through the next stage or a power output of the next stage.

12. The apparatus of claim 9, further comprising:

a second resonate parallel LC load directly couples a power supply to an output of the next stage; and

an input signal coupled to an input of a first stage generates an intermediate signal at the output of the first stage, whereby

the intermediate signal is directly coupled to the input of the next stage.

13. The apparatus of claim 12, whereby

the parallel LC loads comprise parasitic and non-parasitic capacitance and inductance components, and parasitic resistance.

14. The apparatus of claim 13, whereby

the LC loads resonate at a frequency to select a frequency band within an allotted spectrum.

15. The apparatus of claim 12, further comprising:

an output signal at the output of the next stage, whereby

the intermediate signal combines with the second biasing voltage at the output of the first stage and is directly coupled to the input of the next stage to generate the output signal.

16. The apparatus of claim 15, further comprising:

a current source or current sink generating a first current;

a first transistor in saturation; and

a second biasing voltage formed across the first transistor due to the first current flowing though the first transistor.

17. The apparatus of claim 16, further comprising:

a control loop that monitors the second biasing voltage and generates the adjustable biasing voltage.

18. A method of controlling a current in a final stage comprising the steps of:

applying a reference biasing voltage to a control loop;

using the control loop to generate a first biasing voltage;

coupling the first biasing voltage through a first resonant parallel LC load directly to an output of a first stage;

combining an intermediate signal at the output of the first stage directly with the first biasing voltage;

coupling the intermediate signal with the first biasing voltage directly to an input of the final stage; and

adjusting the first biasing voltage, thereby controlling the current in the final stage.

19. The method of claim 18, further comprising the steps of:

coupling a second resonant parallel LC load between a power supply and an output of a final stage; and

coupling the output of the final stage to a driven load.

20. The method of claim 19, whereby

the driven load comprises at least one antenna.

21. An apparatus comprising:

an operational stage of a control loop compares a second biasing voltage to a reference voltage;

a first current through a first transistor generates the reference voltage, whereby the first current is adjustable and

the control loop equalizes the second biasing voltage to the reference voltage;

a first parallel LC load directly couples the second biasing voltage to a gate of a second transistor to control a second current through the second transistor; and

the second transistor scaled to the first transistor by a value, whereby the second current is scaled to the first current by the value.

22. The apparatus of claim 21, whereby

the operational stage uses negative feedback to form the control loop.

23. The apparatus of claim 21, whereby

the operational stage uses positive feedback to form the control loop eliminating the requirement of a compensation network for the operational stage.

24. The apparatus of claim 21, further comprising:

a second parallel LC load directly couples a power supply to an output of the second transistor; and

an input signal coupled to an input of a first stage generates an intermediate signal at the output of the first stage, whereby

the intermediate signal is directly coupled to the gate of the second transistor.

25. The apparatus of claim 24, whereby

the first current adjusts the gain of the second transistor.

26. The apparatus of claim 24, whereby

the LC loads resonate at a frequency to select a frequency band within an allotted spectrum.

27. The apparatus of claim 26, further comprising:

an output signal at the output of the second transistor, whereby

the intermediate signal combines with the second biasing voltage at the gate of the second transistor to generate the output signal.