Direct conversion RF transceiver for wireless communications

• US 7,397,868 B2
• Filed: 05/01/2007
• Issued: 07/08/2008
• Est. Priority Date: 01/18/2002
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Behzad, Arya Reza, Rofougaran, Ahmadreza (Reza), Shi, Zhongming
• Primary Examiner(s): Fan; Chieh M.
• Assistant Examiner(s): Perilla; Jason M.
• Application Number:
  US11/743,143
• Publication Number:
  US 20070201565A1
• Time in Patent Office: 434 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 comprising an antenna for receiving and transmitting high data rate communication signals at radio frequency;

circuitry for adjusting a local oscillation frequency based upon a frequency of a received radio frequency (RF) signal received through the antenna;

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

first received signal strength indication circuit for measuring power levels of signal and interference from a node disposed down stream of the down conversion circuitry and 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

a low noise amplifier operably disposed upstream of the first received signal strength indication circuitry and variable gain amplification circuitry operably disposed down-stream of the low pass filtering circuitry, wherein the transceiver reciprocally adjusts the low noise amplifier and the variable gain amplification circuitry amplification levels based upon outputs of the first and second received signal strength indication circuits.

2. The transceiver of claim 1 wherein the down conversion circuitry provides phase shift keyed base band frequency communication signals.

3. The transceiver of claim 2 wherein the phase shift keyed base band frequency communication signals comprise in-phase and quadrature phase shift keyed signals.

4. The transceiver of claim 1 wherein the circuitry for adjusting is coupled to the 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 variable gain amplification circuitry disposed downstream of the low pass filtering circuitry includes at least one variable gain amplification circuit that further includes a high pass filter to form a high pass variable gain amplifier circuit.

6. The transceiver of claim 1 further comprising an up converter for converting outgoing analog 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 on-chip channel selection low pass filters in at least one of a receive path and a transmit path of the transceiver.

8. A transceiver, comprising;

a transceiver port comprising an antenna for receiving and transmitting radio frequency communication signals wherein received signals are processed in a receive circuit path;

an automatic frequency control circuitry for adjusting a local oscillation frequency (LO) based upon a 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 disposed downstream of the mixing circuitry for low-pass filtering signals;

first received signal strength indication circuit for measuring power levels of signal and interference coupled upstream of the low pass filtering circuitry;

second received signal strength indication circuit for measuring signal power levels coupled downstream of the low pass filtering circuitry;

a plurality of amplifiers operably disposed within the receive circuit path; and

wherein the transceiver is operable to adjust relative power levels of the plurality of amplifiers operably disposed within the receive circuit path to maintain a constant total amplification based upon detected signal strengths produced by the first and second received signal strength indicators.

9. The transceiver of claim 8 wherein the low pass filter blocks interference to allow the second received signal indicator circuit to measure received signal power.

10. The transceiver of claim 8 wherein one of the plurality of amplifiers comprises first high pass variable gain amplification circuitry operably disposed downstream of the low pass filtering circuitry.

11. The transceiver of claim 10 wherein one of the plurality of amplifiers comprises a second high pass variable gain amplifier circuit operably disposed downstream of the first high pass variable gain amplification circuitry.

12. The transceiver of claim 11 wherein one of the plurality of amplifiers comprises a third high pass variable gain amplifier circuit operably disposed downstream of the first high pass variable gain amplification circuitry.

13. The transceiver of claim 8 wherein the automatic frequency control circuitry provides the local oscillation frequency to support reception of quadrature phase shift keyed signals.

14. The transceiver of claim 8 wherein the automatic frequency control circuitry produces an adjusted local oscillation frequency signal output from a local oscillator based upon received signals.

15. The transceiver of claim 8 further including high pass filter circuitry for removing DC offset.

16. The transceiver of claim 15 wherein the high pass filtering circuitry is for removing low frequency interference.

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

18. The transceiver of claim 8 further including resistive capacitive (RC) calibration circuitry for automatically tuning on chip filters in at least one of the receive circuit path and a transmit circuit path of the transceiver.

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

receiving and amplifying wideband or high data rate radio frequency (RF) communication signals in a receive circuit path;

adjusting a local oscillation frequency (LO) based upon the received signals;

down converting the received signals from RF to a lower frequency based upon the adjusted LO;

measuring power levels of signal and interference of the down converted received signals from a first node disposed up-stream of low pass filtering circuitry;

measuring power levels of the down converted received signals from a second node disposed down-stream of the low pass filtering circuitry; and

adjusting amplification levels in the receive circuit path based upon the measured power levels at the first and second nodes.

20. The method of claim 19 further including removing a direct current (DC) offset.

21. The method of claim 19 further including removing low frequency interference.

22. The method of claim 19 wherein the amplification levels are adjusted to maintain a constant amount of amplification.

23. The method of claim 19 further including the step of receiving center channel frequency information from a pilot signal and determining a difference between the received RF frequency and an expected frequency.

24. The method of claim 23 wherein the difference is determined by measuring an actual center frequency of the received signals.