Low-power CDMA receiver

• US 6,668,028 B1
• Filed: 03/29/2000
• Issued: 12/23/2003
• Est. Priority Date: 03/29/2000
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.), Sony Electronics Inc. (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.), Sony Electronics Inc. (Sony Group Corp.)
• Inventors: Wieck, Christopher Peter
• Primary Examiner(s): Corrielus, Jean B.
• Application Number:
  US09/539,165
• Time in Patent Office: 1,364 Days
• Field of Search: 375/349, 375/295, 375/346, 375/316, 375/345, 375/319, 375/224, 375/227, 375/228, 370/335, 370/342, 370/136
• US Class Current: 375/349
• CPC Class Codes: H03F 1/0272 by using a signal derived from the output signal
• CPC Class Codes: H03F 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/372 Noise reduction and elimination in amplifier
• CPC Class Codes: H03F 2203/7239 the gated amplifier being switched on or off by putting into parallel or not, by choosing between amplifiers and shunting lines by one or more switch(es)
• CPC Class Codes: H03F 3/1935 with junction-FET devices
• CPC Class Codes: H04B 1/109 by improving strong signal performance of the receiver when strong unwanted signals are present at the receiver input

Abstract

A first amplifier amplifies a radio frequency signal into a first stage signal, a detector produces a bypass signal based on the environment in which the receiver is operating. A switch provides the first stage signal or the first stage signal filtered by a radio frequency filter based on the bypass signal is not asserted. Optionally, the detector also produces a bias control signal and bias generators set the bias levels of the amplifiers according to the bias control signal. The invention increases linear range RF amplification stages. Power consumption is reduced by reducing the amplification (and optionally the bias levels) used under typical conditions. The invention is advantageous for applications where power is at a premium and the receiver, or at least its front end, operates while the device is in standby mode. Such applications include mobile, portable and hand held pagers and wireless telephones and Internet connections.

Claims

1. A radio frequency receiver, comprising:

a first amplifier configured to produce a first stage signal by amplifying a radio frequency signal;

a radio frequency filter;

a second amplifier;

a signal level detector configured to assert a bypass signal only when the radio frequency signal is sufficiently strong such that a threshold is reached;

a switch configured to provide a switched signal, wherein when the bypass signal is asserted the switched signal is substantially the first stage signal without being filtered by the radio frequency filter, and when the bypass signal is not asserted the switched signal is the first stage signal filtered by the radio frequency filter and amplified by the second amplifier; and

wherein the radio frequency signal is a code division multiple access (CDMA) signal and the bypass signal is asserted for a signal strength corresponding to a received signal of minus 90 dBm.

2. A radio frequency receiver, comprising:

a first amplifier configured to produce a first stage signal by amplifying a radio frequency signal;

a radio frequency filter;

a second amplifier;

a signal level detector configured to assert a bypass signal only when the radio frequency signal exceeds a threshold;

a switch configured to provide a switched signal, wherein when the bypass signal is asserted the switched signal is substantially the first stage signal without being filtered by the radio frequency filter, and when the bypass signal is not asserted the switched signal is the first stage signal filtered by the radio frequency filter and amplified by the second amplifier;

a radio frequency to intermediate frequency converter configured to receive the switched signal and to convert it to a first intermediate frequency signal; and

an intermediate frequency filter configured to filter the first intermediate frequency signal to produce a second intermediate frequency signal;

wherein the signal level detector asserts the bypass signal based on a level of the second intermediate frequency signal.

3. A radio frequency receiver, comprising:

a first amplifier means for producing a first stage signal by amplifying a radio frequency signal;

a radio frequency filter means;

a second amplifier means;

a signal level detector means for asserting a bypass signal only when the radio frequency signal reaches a threshold;

a switch means for providing a switched signal, wherein when the bypass signal is asserted the switched signal is substantially the first stage signal without being filtered by the radio frequency filter means, and when the bypass signal is not asserted the switched signal is the first stage signal filtered by the radio frequency filter means and amplified by the second amplifier means; and

wherein the radio frequency signal is a code division multiple access (CDMA) signal and the bypass signal is asserted for a signal strength corresponding to a received signal of minus 90 dBm.

4. A method of receiving a radio frequency signal, comprising:

amplifying the radio frequency signal without filtering to produce a first signal;

filtering and amplifying the first signal to produce a second signal;

detecting a signal level corresponding to the radio frequency signal;

asserting a bypass signal only when the signal level is sufficiently strong such that a threshold is exceeded;

switching between the first signal when the bypass signal is asserted, and the second signal when the bypass signal is not asserted; and

wherein the radio frequency signal is a code division multiple access (CDMA) signal and the bypass signal is asserted for a signal strength corresponding to a received signal of minus 90 dBm.

5. A radio frequency receiver, comprising:

a first radio frequency amplifier, having a first bias level, configured to produce a first stage signal by amplifying an input signal;

a radio frequency filter;

a second radio frequency amplifier, having a second bias level;

a signal level detector configured to produce a bypass signal only when a first signal strength of the receiver is sufficiently strong such that a threshold is reached, and to produce a bias control signal according to a second signal strength of the receiver; and

a switch configured to provide a switched signal, wherein when the bypass signal is asserted, the switched signal is substantially the first stage signal without being filtered by the radio frequency filter, and when the bypass signal is not asserted, the switched signal is the first stage signal filtered by the radio frequency filter and amplified by the second amplifier;

a first bias generator configured to generate the first bias level according to the bias control signal; and

a second bias generator configured to generate the second bias level according to the bias control signal.

6. The receiver of claim 5, wherein the radio frequency filter is a transmission rejection filter and the receiver is used in a transceiver.

7. The receiver of claim 5, wherein the radio frequency signal is a code division multiple access (CDMA) signal.

8. The receiver of claim 5, wherein the radio frequency signal is a code division multiple access (CDMA) signal and the bypass signal is asserted for a signal strength corresponding to a received signal of minus 90 dBm.

9. The receiver of claim 5, wherein the first signal strength and the second signal strength are the same.

10. The receiver of claim 5, wherein the first signal strength is based on a signal from one stage of the receiver and the second signal strength is based on a signal from another stage of the receiver.

11. The receiver of claim 5, wherein the signal level detector is further configured to produce the bias control signal based on the first signal strength and based on the bypass signal.

12. The receiver of claim 5, wherein:

the first signal strength is based on a signal from a first stage of the receiver;

the second signal strength is based on a signal from a second stage of the receiver, the second stage being subsequent to the first stage; and

the signal level detector is further configured to produce the bias control signal based on the first signal strength and based on the bypass signal.

13. The receiver of claim 5, wherein at least one of the bias generator circuits comprise a variable resistance circuit.

14. The receiver of claim 5, wherein at least one of the bias generator circuits is configured to shut down in response to a shutdown control signal.

15. The receiver of claim 5, further comprising:

a bias adjustment circuit configured to receive the bias control signal from the detector and to adjust the bias control signal prior to use by the bias generators.

16. The receiver of claim 15, wherein the bias adjustment circuit comprises a circuit selected from an operational amplifier circuit and a sample and hold circuit.

17. The receiver of claim 15, wherein the configuration of the bias adjustment circuit is selected from a configuration that conditions the bias control signal, a configuration that scales the bias control signal, a configuration that responds to the bias level as regulating feedback, a configuration that holds the bias level at a particular level when the receiver is operating under an idle condition, and a configuration that holds the bias level at a particular level when the receiver is operating under an idle condition and that generally increases the bias level as the signal strength increases.

18. A radio frequency receiver, comprising:

a first radio frequency amplifier means, having a first bias level, for producing a first stage signal by amplifying an input signal;

a radio frequency filter means;

a second radio frequency amplifier means, having a second bias level;

a signal level detector means for producing a bypass signal only when a first signal strength of the receiver exceeds a threshold, and for producing a bias control signal according to a second signal strength of the receiver; and

a switch means for providing a switched signal, wherein when the bypass signal is asserted, the switched signal is substantially the first stage signal without being filtered by the radio frequency filter means, and when the bypass signal is not asserted, the switched signal is the first stage signal filtered by the radio frequency filter means and amplified by the second amplifier means;

a first bias means for generating the first bias level according to the bias control signal; and

a second bias means for generating the second bias level according to the bias control signal.

19. The receiver of claim 18, wherein the radio frequency filter means is a transmission rejection filter and the receiver is used in a transceiver.

20. The receiver of claim 18, wherein the radio frequency signal is a code division multiple access (CDMA) signal.

21. The receiver of claim 18, wherein the radio frequency signal is a code division multiple access (CDMA) signal and the bypass signal is asserted for a signal strength corresponding to a received signal of minus 90 dBm.

22. The receiver of claim 18, wherein at least one of the bias generator circuits is configured to shut down in response to a shutdown control signal.

23. The receiver of claim 18, wherein:

the first signal strength is based on a signal from a first stage of the receiver;

the second signal strength is based on a signal from a second stage of the receiver, the second stage being subsequent to the first stage; and

the signal level detector is further configured to produce the bias control signal based on the first signal strength and based on the bypass signal.

24. The receiver of claim 18, further comprising:

a bias adjustment means for adjusting the bias control signal from the detector means prior to use by at least one of the bias generator means.

25. The receiver of claim 24, wherein the bias adjustment means comprises a circuit selected from an operational amplifier circuit and a sample and hold circuit.

26. The receiver of claim 24, wherein the bias adjustment means is selected from a means for conditioning the bias control signal, a means for scaling the bias control signal, a means for responding to the bias level as regulating feedback, a means for holding at least one of the bias levels at a particular level when the receiver is operating under an idle condition, and a means for holding at least one of the bias levels at a particular level when the receiver is operating under an idle condition and that generally increases the bias level as the signal strength increases.