Quadrature modulation circuits and systems supporting multiple modulation modes at gigabit data rates
View Patent ↗A quadrature modulation circuit includes a mixer circuit including an integrated sign modulation control circuit and a plurality of mixer ports. The mixer ports include a first input port, a second input port, an output port and a sign modulation control port. The modulation circuit generates a modulated signal by operation of the mixer circuit multiplying a modulating signal applied to the first input port with a carrier signal applied to the second input port to generate a mixed signal output from the output port, and by operation of the integrated sign modulation control circuit controlling polarity switching of a signal at one of the mixer ports in response to a sign modulation control signal input to the sign modulation control port.
1. A quadrature modulation circuit, comprising:
a mixer circuit including an in-phase (I) mixer and a quadrature-phase (Q) mixer; and
a summing circuit coupled to an output of the mixer circuit;
wherein the I mixer comprises:
a plurality of I mixer ports including a baseband input port, an output port, an LO (local oscillator) port and an I sign control port; and
an integrated I sign modulation control circuit to control polarity switching of a signal at one of the I mixer ports in response to an I sign modulation control signal input to the I sign control port;
wherein the Q mixer comprises:
a plurality of Q mixer ports including a baseband input port, an output port, an LO (local oscillator) port and a Q sign control port; and
an integrated Q sign modulation control circuit to control polarity switching of a signal at one of the Q mixer ports in response to a Q sign modulation control signal input to the Q sign control port; and
wherein the summing circuit generates a modulated signal by adding signals output from the I and Q mixers,
wherein the I mixer comprises an integrated I channel amplitude modulation control circuit to modulate an amplitude of an I-channel signal in response to an I gain control signal applied to an I gain control port of the I mixer, and wherein the Q mixer comprises an integrated Q-channel amplitude modulation control circuit to modulate an amplitude of a Q-channel signal in response to a Q gain control signal applied to a Q gain control port of the Q mixer,
wherein the quadrature modulation circuit supports FSK (frequency-shift key), PSK (phase-shift key) and ASK (amplitude-shift key) modulation modes and simultaneous ASK/FSK and ASK/PSK modulation modes,
wherein the quadrature modulation circuit performs ASK modulation by applying quadrature LO signals to the LO ports of the I and Q mixers, applying fixed-level DC signals to the baseband input ports of the I and Q mixers, applying fixed-level DC signals to the I and Q sign modulation control ports of the I and Q mixers, and applying a single digital data signal to both the I and Q gain control ports of the I and Q mixers to modulate the amplitude of I-channel and Q-channel signals, to thereby generate an ASK modulated signal the represents binary data of the digital data signal.
2. The circuit of claim 1 , wherein the quadrature modulation circuit performs PSK modulation by phase modulating an LO signal using a digital data signal applied to at least one of the I or Q sign modulation control ports to control polarity switching, to thereby generate a PSK modulated signal that represents binary data of the digital data signal.
3. The circuit of claim 1 , wherein the quadrature modulation circuit performs FSK modulation by frequency modulating a complex baseband input signal using a digital data signal applied to at least one of the I or Q sign modulation control ports to control polarity switching, to thereby generate a FSK modulated signal that represents binary data of the digital data signal.
4. The circuit of claim 1 , wherein the quadrature modulation circuit performs MSK (minimum shift key) modulation by inputting quadrature LO signals to the LO ports of the I and Q mixers, inputting fixed-frequency sinusoidal quadrature signals to the baseband input ports of the I and Q mixers, inputting a first digital data signal as an I sign modulation control signal to control polarity switching at one of the I mixer ports, and inputting a second digital data signal as a Q sign modulation control signal to control polarity switching at one of the Q mixer ports, to thereby generate a frequency modulated signal that represents binary data of the first and second digital data signals.
5. The circuit of claim 1 , wherein the quadrature modulation circuit performs BPSK (binary phase-shift key) modulation by inputting quadrature LO signals to the LO ports of the I and Q mixers, inputting fixed-level DC signals to the baseband input ports of the I and Q mixers, inputting one of the I and Q sign modulation control signals as a fixed-level DC signal and inputting the other one of the I and Q sign modulation control signals as a digital data signal to control polarity switching at one of the I mixer ports or Q mixer ports, to thereby generate a phase modulated signal that represents binary data of the digital data signal.
6. The circuit of claim 1 , wherein the quadrature modulation circuit performs QPSK (quadrature phase-shift key) modulation by inputting quadrature LO signals to the LO ports of the I and Q mixers, inputting fixed-level DC signals to the baseband input ports of the I and Q mixers, inputting a first digital data signal as an I sign modulation control signal to control polarity switching at one of the I mixer ports, and inputting a second digital data signal as a Q sign modulation control signal to control polarity switching at one of the Q mixer ports, to thereby generate a phase modulated signal that represents binary data of the first and second digital data signals.
7. The circuit of claim 1 , wherein the mixer circuit is a double balanced active mixer and wherein the I and Q mixers each comprise a mixing stage and transconductor stage.
8. The circuit of claim 7 , wherein the integrated I and Q sign modulation control circuits are formed as part of the transconductor stages of respective I and Q mixers.
9. The circuit of claim 7 , wherein the integrated I and Q sign modulation control circuits are formed as part of the mixing stages of respective I and Q mixers.
10. The circuit of claim 1 , wherein the I and Q mixers each comprise a slew rate control circuit to control a slew rate of polarity switching by the I sign and Q sign modulation control circuits, respectively.
11. The circuit of claim 10 , wherein the slew rate control circuits are configured to adjust the slew rate of polarity switching by the I and Q sign modulation circuits in response to a slew rate control signal applied to a slew rate control port of the mixer circuit.
12. The circuit of claim 1 , wherein the ASK modulation is OOK (on-off keying) modulation where the I and Q integrated amplitude modulation control circuits control respective I and Q channel signal amplitude by switching between gain states of 0 and 1 relative to full gain.
13. The circuit of claim 1 , wherein the ASK modulation is BASK (binary amplitude-shift key modulation) where the I and Q integrated amplitude modulation control circuits control respective I and Q-channel signal amplitude by switching between two different gain levels, where one or both of the gain levels are fixed or programmable.
14. The circuit of claim 1 , wherein quadrature modulation circuit performs ASK modulation simultaneously with FSK modulation by inputting quadrature LO signals to the LO ports of the I and Q mixers, inputting fixed-frequency sinusoidal quadrature IQ signals to the baseband input ports of the I and Q mixers, applying a first digital data signal to both the I and Q gain control ports of the I and Q mixers to modulate the amplitude of I-channel and Q-channel signals by switching between, two different gain levels and by applying a second digital data signal to at least one of the I or Q sign control ports to control polarity switching of an I or Q-channel signal.
15. The circuit of claim 1 , wherein quadrature modulation circuit performs ASK modulation simultaneously with PSK modulation by inputting quadrature LO signals to the LO ports of the I and Q mixers, inputting fixed-level DC signals to the baseband input ports of the I and Q mixers, applying a first digital data signal to the I gain control port of the I mixer to modulate the amplitude of an I-channel signal by switching between two different gain levels, applying a second digital data signal to the Q gain control port of the Q mixer to modulate the amplitude of a Q-channel signal by switching between two different gain levels, and by applying a third digital data signal to at least one of the I or Q sign control ports to control polarity switching of the I or Q-channel signal.
16. The circuit of claim 1 , wherein the mixer circuit is a double balanced active mixer, wherein the I and Q mixers each comprise a mixing stage and transconductor stage, wherein the integrated I and Q amplitude modulation control circuits are formed as part of the transconductor stages of the I and Q mixers, respectively.
17. The circuit of claim 3 , wherein the digital data signal is synchronized with a fixed-frequency sinusoidal signal applied to a baseband input port of the I or Q mixer such that polarity switching is performed synchronously at zero crossings of the fixed-frequency sinusoidal signal to realize a phase-continuous frequency switch.
18. A quadrature modulation circuit, comprising:
a mixer circuit including an in-phase (I) mixer and a quadrature-phase (Q) mixer; and
a summing circuit coupled to an output of the mixer circuit;
wherein the I mixer comprises:
a plurality of I mixer ports including a baseband input port, an output port, an LO (local oscillator) port and an I sign control port; and
an integrated I sign modulation control circuit to control polarity switching of a signal at one of the I mixer ports in response to an I sign modulation control signal input to the I sign control port;
wherein the Q mixer comprises:
a plurality of Q mixer ports including a baseband input port, an output port, an LO (local oscillator) port and a Q sign control port; and
an integrated Q sign modulation control circuit to control polarity switching of a signal at one of the Q mixer ports in response to a Q sign modulation control signal input to the Q sign control port; and
wherein the summing circuit generates a modulated signal by adding signals output from the I and Q mixers,
wherein the quadrature modulation circuit performs BFSK (binary frequency-shift key) modulation by inputting quadrature LO signals to the LO ports of the I and Q mixers, inputting fixed-frequency sinusoidal quadrature IQ signals to the baseband input ports of the I and Q mixers, inputting one of the I and Q sign modulation control signals as a fixed-level DC signal and inputting the other one of the I and Q sign modulation control signals as a digital data signal to control polarity switching at one of the I mixer ports or Q mixer ports, to thereby generate a frequency modulated signal that represents binary data of the digital data signal.