Transceiver system with common receiver and transmitter oscillator
View Patent ↗A transceiver system including a common receiver and transmitter oscillator. The transceiver system may include transmitter circuitry, receiver circuitry, and a first oscillator. The first oscillator may provide a transmit frequency to a mixer in the transmitter circuitry to generate a transmitter RF signal. Furthermore, the first oscillator may also provide the transmit frequency to a first stage mixer in the receiver circuitry to down-convert a receiver RF signal from a receive frequency to an intermediate frequency (IF). The receiver circuitry may include a second oscillator and a second stage mixer. The second oscillator may provide an IF frequency to the second stage mixer to down-convert receiver signals at IF to a lower frequency. The receiver circuitry may filter out transmitter RF feedthrough signals without using a SAW filter. The transmitter circuitry, the receiver circuitry, and the first oscillator may be included in a single IC.
1. A transceiver system comprising: transmitter circuitry configured to generate a transmitter radio frequency (RF) signal; a first oscillator coupled to a mixer in the transmitter circuitry and configured to provide a transmit frequency signal to the mixer to generate the transmitter RF signal; receiver circuitry configured to receive a receiver RF signal; wherein the first oscillator is coupled to a first stage mixer in the receiver circuitry and configured to provide the transmit frequency signal to the first stage mixer to down-convert the receiver RF signal from a receive frequency to an intermediate frequency (IF); wherein the first stage mixer is configured to down-convert the transmitter feedthrough RF signal from the transmit frequency to a baseband frequency; and a capacitor coupled in series to an output of the first stage mixer and configured to filter out a transmitter RF feedthrough signal at the baseband frequency.
2. The transceiver system of claim 1 , wherein the receiver circuitry is configured to filter out the transmitter RF feedthrough signal without using an external filter.
3. The transceiver system of claim 1 , wherein the receiver circuitry is configured to filter out the transmitter RF feedthrough signal without using a surface acoustic wave (SAW) filter.
4. The transceiver system of claim 3 , wherein the receiver circuitry further comprises an IF filter coupled to the capacitor.
5. The transceiver system of claim 1 , further comprises a phase-locked loop (PLL) operable to drive the first oscillator.
6. The transceiver system of claim 1 , further comprising a second oscillator coupled to the receiver circuitry, wherein the second oscillator is configured to provide an IF frequency to the receiver circuitry to down-convert the receiver IF signal to a lower frequency.
7. The transceiver system of claim 6 , wherein the first oscillator is an LC-based voltage-controlled oscillator (VCO) and the second oscillator is a ring oscillator.
8. The transceiver system of claim 6 , wherein the receiver circuitry further comprises a second stage mixer coupled to the second oscillator, wherein the second oscillator is configured to provide an IF frequency to the second stage mixer to down-convert the receiver IF signal to a lower frequency.
9. The transceiver system of claim 1 , further comprising divider circuitry to derive the transmit frequency signal.
10. The transceiver system of claim 1 , configured to implement WCDMA protocol.
11. The transceiver system of claim 1 , configured to implement CDMA protocol.
12. The transceiver system of claim 1 , wherein the transmitter circuitry and the receiver circuitry operate concurrently.
13. The transceiver system of claim 1 , wherein the transmitter circuitry, the receiver circuitry, and the first oscillator are included in a single IC.
14. The transceiver system of claim 1 , wherein the transmitter circuitry, the receiver circuitry, and the first oscillator are included in two or more ICs.
15. A method for processing RF signals in a transceiver system, wherein the transceiver system includes receiver circuitry, transmitter circuitry, and a first oscillator, the method comprising: the first oscillator providing a transmit frequency signal to a mixer in the transmitter circuitry to generate a transmitter RF signal; the receiver circuitry receiving a receiver RF signal; the first oscillator further providing the transmit frequency signal to a first stage mixer in the receiver circuitry to down-convert the receiver RF signal from a receive frequency to an intermediate frequency (IF); the first stage mixer down-converting a transmitter RF feedthrough signal from the transmit frequency to a baseband frequency; and filtering out a transmitter RF feedthrough signal at the baseband frequency using a capacitor coupled in series to an output of the first stage mixer.
16. The method of claim 15 , wherein said filtering out a transmitter RF feedthrough signal includes filtering out the transmitter RF feedthrough signal without using a SAW filter.
17. The method of claim 15 , wherein the receiver circuitry further includes a second oscillator and a second stage mixer, wherein the method further includes the second oscillator providing an IF frequency to the second stage mixer and the second stage mixer down-converting the receiver IF signal to a lower frequency.
18. A communication system comprising: an antenna configured to transmit and receive RF signals; and a transceiver system coupled to the antenna and including: transmitter circuitry configured to generate a transmitter RF signal; a first oscillator coupled to a mixer in the transmitter circuitry and configured to provide a transmit frequency signal to the mixer to generate the transmitter RF signal; and receiver circuitry configured to receive a receiver RF signal; wherein the first oscillator is coupled to a first stage mixer in the receiver circuitry and configured to provide the transmit frequency signal to the first stage mixer to down-convert the receiver RF signal from a receive frequency to an intermediate frequency (IF); wherein the first stage mixer is configured to down-convert the transmitter feedthrough RF signal from the transmit frequency to a baseband frequency; and a capacitor coupled in series to an output of the first stage mixer and configured to filter out a transmitter RF feedthrough signal at the baseband frequency.
19. A WCDMA communication system comprising:
an antenna configured to transmit and receive RF signals; and
a transceiver system coupled to the antenna and including:
transmitter circuitry configured to generate a transmitter RF signal;
a first oscillator coupled to a mixer in the transmitter circuitry and configured to provide a transmit frequency signal to the mixer to generate the transmitter RF signal;
receiver circuitry configured to receive a receiver RF signal, wherein the receiver circuitry includes a first stage mixer and a second stage mixer;
a capacitor coupled in series to an output of the first stage mixer and configured to filter out a transmitter RF feedthrough signal;
wherein the first oscillator is further configured to provide the transmit frequency signal to the first stage mixer to down-convert the receiver RF signal to an IF frequency; and
a second oscillator coupled to the receiver circuitry, wherein the second oscillator is configured to provide an IF frequency to the second stage mixer to down-convert the receiver IF signal to a lower frequency.