Direct conversion RF transceiver for wireless communications

• US 7,212,586 B2
• Filed: 01/18/2002
• Issued: 05/01/2007
• Est. Priority Date: 01/18/2002
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Behzad, Arya Reza, Shi, Zhongming, Rofougaran, Reza
• Primary Examiner(s): Fan; Chieh M.
• Assistant Examiner(s): Perilla; Jason M.
• Application Number:
  US10/052,870
• Publication Number:
  US 20030138032A1
• Time in Patent Office: 1,929 Days
• Field of Search: 375/219, 375/316, 375/324, 375/344, 375/345, 375/346, 455/130
• US Class Current: 375/316
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H03J 7/04 where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
• CPC Class Codes: H04B 1/04 Circuits
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22
• CPC Class Codes: H04B 1/408 the transmitter oscillator frequency being identical to the receiver local oscillator frequency
• CPC Class Codes: H04B 2001/0416 having gain or transmission power control

Abstract

A single chip radio transceiver includes circuitry that enables received wideband RF signals to be down converted to base band frequencies and base band signals to be up converted to wideband RF signals prior to transmission without requiring conversion to an intermediate frequency. The circuitry includes a low noise amplifier, automatic frequency control circuitry for aligning the LO frequency with the frequency of the received RF signals, signal power measuring circuitry for measuring the signal to signal and power ratio and for adjusting frontal and rear amplification stages accordingly, and finally, filtering circuitry to filter high and low frequency interfering signals including DC offset.

Claims

1. A transceiver, comprising:

a transceiver port for receiving and transmitting high data rate communication signals at radio frequency;

automatic frequency control circuitry for adjusting a local oscillation frequency based upon a detected difference between an actual frequency of the received communication signals and an expected frequency of the received communication signals wherein the automatic frequency control circuitry produces an adjusted local oscillation;

down conversion circuitry to receive the adjusted local oscillation from the automatic frequency control circuitry and further coupled to receive the communication signals at radio frequency wherein the down conversion circuitry is operable to produce base band frequency communication signals based upon the adjusted local oscillation and upon the received communication signals at radio frequency;

low pass filtering circuitry coupled to receive the base band frequency signals from the down conversion circuitry, the low pass filtering circuitry for removing a DC offset and low frequency interference to produce low-pass filtered communication signals;

high pass filtering circuitry coupled to receive the low-pass filtered communication signals, the high pass filtering circuitry for filtering interference signals that are at a frequency range that is higher than a specified frequency channel of a down converted base band channel;

first received signal strength indication circuit for measuring power levels of signal and interference from a node disposed up-stream of the low pass filtering circuitry; and

second received signal strength indication circuit for measuring signal power levels from a node disposed down-stream of the low pass filtering circuitry.

2. The transceiver of claim 1 wherein the automatic frequency control circuitry comprises signal generation circuitry that provides phase shift keyed signals.

3. The transceiver of claim 2 wherein the phase shift keyed signal generation circuitry comprises quadrature phase shift keyed signal generation circuitry.

4. The transceiver of claim 1 wherein the automatic frequency control circuitry is coupled to transceiver port and is operable to adjust the local oscillation frequency to a desired radio frequency (RF) channel.

5. The transceiver of claim 1 wherein the high pass filtering circuitry and variable gain amplification circuitry are combined to form high pass variable gain amplifier circuit.

6. The transceiver of claim 1 further comprises an up converter for converting base band signals to radio frequency (RF) signals for transmission from the transceiver.

7. The transceiver of claim 1 further including resistive capacitive (RC) calibration circuitry to automatically tune the on-chip channel selection low pass filters.

8. A transceiver, comprising;

a transceiver port for receiving and transmitting radio frequency communication signals;

an automatic frequency control circuit for adjusting a local oscillation (LO) based upon the center frequency of a received radio frequency (RF) signal;

mixing circuitry for down converting the received RF signal based upon the adjusted LO;

low pass filtering circuitry for removing a direct current (DC) offset and low frequency interference from signals in the received signal path, downstream of the mixing circuitry for low-pass filtering signals in a receive circuit path;

first received signal strength indication circuit for measuring power levels of signal and interference from a node disposed up-stream of low pass filtering circuitry; and

second received signal strength indication circuit for measuring signal power levels from a node disposed down-stream of the low pass filtering circuitry.

9. The transceiver of claim 8 further including dual received signal indication circuits, which dual received signal indicator circuits are for measuring received signal power and received signal and interference power.

10. The transceiver of claim 8 further including high pass variable gain amplification circuitry.

11. The transceiver of claim 10 further including a second high pass variable gain amplifier circuit.

12. The transceiver of claim 11 further including a third high pass variable gain amplifier circuit.

13. The transceiver of claim 8 wherein the automatic frequency control circuitry includes quadrature phase shift keyed signal generation circuitry.

14. The transceiver of claim 8 wherein the automatic frequency control circuitry receives base band quadrature signals and produces an adjusted local oscillation (LO) signal output from a local oscillator.

15. The transceiver of claim 8 further including an up converter for up converting base band signals to radio frequency signals for transmission from the transceiver port.

16. The transceiver of claim 8 further including resistive capacitive (RC) calibration circuitry for automatically tuning the on chip filters.

17. A method in a high data rate communication transceiver comprising:

receiving and amplifying wideband high data rate radio frequency (RF) communication signals;

adjusting a local oscillation (LO) frequency to compensate for a difference in a received frequency and an expected frequency of the received high data rate RF communication signals;

down converting the received signals from RF to base band frequency;

applying the down converted base band frequency signals to low pass filters and amplifiers;

measuring power levels of signal and interference from a node disposed up-stream of low pass filtering circuitry; and

measuring signal power levels from a node disposed down-stream of the low pass filtering circuitry.

18. The method of claim 17 wherein the applying step removes the direct current (DC) offset.

19. The method of claim 17 wherein the applying step removes low frequency interference.

20. The method of claim 17 further including the step of sensing the power level of the received signals.

21. The method of claim 17 further including the step of sensing a power level of received signals and interference.

22. The method of claim 17 further including the step of setting a first amplification level based upon a ratio of signal-to-signal and interference power levels.

23. The method of claim 22 further including the step of setting a second amplification level based upon a ratio of signal to signal plus interference power levels.

24. The method of claim 23 wherein the first and second amplification levels, when summed, provide a constant amount of amount of amplification.

25. The method of claim 17 further including the step of receiving center channel frequency information from a pilot signal and determining a difference between the received RF frequency and the expected frequency.

26. The method of claim 25 wherein the difference is determined by measuring an actual center frequency for the received signal.

27. A transceiver, comprising:

frequency control circuitry operable to compensate for a detected difference between an actual frequency of the received communication signals and an expected frequency of the received communication signal;

low pass filtering circuitry disposed downstream of the mixing circuitry for low-pass filtering signals in a receive circuit path;

first received signal strength indication circuit for measuring power levels of signal and interference from a node disposed up-stream of low pass filtering circuitry;

second received signal strength indication circuit for measuring signal power levels from a node disposed down-stream of the low pass filtering circuitry; and

multiple high pass variable gain amplifier circuits coupled to receive the output of the low pass filtering circuitry wherein the the low pass filtering circuitry removes low frequency interference and a direct current (DC) offset and wherein the high pass variable gain amplification circuits provide signal amplification.

28. The transceiver of claim 27 wherein the frequency control circuitry includes circuitry for measuring a center channel frequency and for determining a difference between the measured center channel frequency and a specified center channel frequency.

29. The transceiver of claim 27 further including signal generation circuitry for generating quadrature phase shift keyed signals.

30. The transceiver of claim 27 further including a mixer for producing local oscillator output signals at a specified frequency.