Method and apparatus for clock phase generation
A method, non-transitory computer readable medium, and circuit for clock phase generation are disclosed. The circuit includes an injection locked oscillator, a loop controller, and a phase interpolator. The injection locked oscillator includes an input for receiving an injected clock signal and an output for forwarding a set of fixed clock phases. The loop controller includes an input for receiving a phase separation error of the fixed clock phases and an output for forwarding a supply voltage derived from the phase separation error. The supply voltage matches the free running frequency of the injection locked oscillator to a frequency of the injected clock signal. The phase interpolator includes an input for receiving the set of fixed clock phases directly from the injection locked oscillator, an input for receiving the supply voltage from the loop controller, and an output for forwarding an arbitrary clock phase.
1. A circuit, comprising:
an injection locked oscillator including an input for receiving an injected clock signal and an output for forwarding a set of fixed clock phases;
a loop controller including an input for receiving a phase separation error of the set of fixed clock phases and an output for forwarding a supply voltage derived from phase separation error, wherein the supply voltage matches a free running frequency of the injection locked oscillator to a frequency of the injected clock signal; and
a phase interpolator including an input for receiving the set of fixed clock phases directly from the injection locked oscillator, an input for receiving the supply voltage from the loop controller, and an output for forwarding an arbitrary clock phase,
wherein the phase interpolator comprises:
a plurality of multiplexers, each multiplexer of the plurality of multiplexers including a plurality of inputs, and each input of the plurality of inputs being configured for receiving one clock phase of the set of fixed clock phases; and
a plurality of inverters, each inverter of the plurality of inverters having an input for receiving an output of one multiplexer of the plurality of multiplexers.
2. The circuit of claim 1 , wherein the loop controller finds the supply voltage by driving the phase separation error toward zero.
3. The circuit of claim 1 , further comprising:
a phase separation error detector for receiving the set of fixed clock phases and an output for forwarding the phase separation error of the set of fixed clock phases.
4. The circuit of claim 3 , wherein the injection locked oscillator, the phase separation error detector, and the loop controller comprise a frequency locking loop driven by the phase separation error detector.
5. The circuit of claim 3 , wherein the phase separation error detector is programmed to perform in-phase and quadrature error detection on the set of fixed clock phases.
6. The circuit of claim 1 , further comprising:
a set of buffers having an input for receiving the arbitrary clock phase and an input for receiving the supply voltage.
7. The circuit of claim 1 , wherein the circuit is part of a serializer/deserializer.
8. The circuit of claim 1 , wherein the loop controller comprises a charge pump and a loop filter.
9. The circuit of claim 1 , wherein the loop controller comprises an accumulator.
10. The circuit of claim 1 , wherein the injection locked oscillator comprises:
a plurality of complementary metal-oxide semiconductor inverters arranged to form a voltage controlled oscillator, wherein each of the plurality of complementary metal-oxide semiconductor inverters includes an output for forwarding one clock phase of the set of fixed clock phases; and
a single complementary metal-oxide semiconductor inverter having an input for receiving the injected clock signal.
11. The circuit of claim 10 , wherein the single complementary metal-oxide semiconductor further includes an output shorted to one clock phase of the set of fixed clock phases.
12. The circuit of claim 1 , wherein each multiplexer of the plurality of multiplexers is implemented using a plurality of complementary metal-oxide semiconductor tri-state inverters.
13. The circuit of claim 1 , wherein each inverter of the plurality of inverters is implemented as an array of complementary metal-oxide semiconductor tri-state inverters, and phase mixing of the set of fixed clock phases is accomplished by enabling different numbers of complementary metal-oxide semiconductor tri-state inverters in the plurality of inverters.
14. A circuit, comprising:
an injection locked oscillator including an input for receiving an injected clock signal and an output for forwarding a set of fixed clock phases;
a loop controller including an input for receiving a phase separation error of the set of fixed clock phases and an output for forwarding a supply voltage derived from phase separation error, wherein the supply voltage matches a free running frequency of the injection locked oscillator to a frequency of the injected clock signal; and
a phase interpolator including an input for receiving the set of fixed clock phases directly from the injection locked oscillator, an input for receiving the supply voltage from the loop controller, an input for receiving a digital control signal from a clock and data recovery circuit, and an output for forwarding an arbitrary clock phase, wherein the phase interpolator is configured to select one of the set of fixed clock phases to output as the arbitrary clock phase using the digital control signal.