Signal generator
AssigneeAdvantest Corporation
InventorHitoshi Kitayoshi
Life of this patent
Estimating the term…
Abstract
In a phase accumulation type signal generatorm when an adder of a phase accumulator yields a carry output, a difference circuit generates an analog voltage V.sub.1 =a.sub.2 (n-k.sub.s) which is in proportion to the difference between the output k.sub.s of the adder and a phase add amount n. A ramp function voltage generator generates a ramp function voltage V(t)=nfa.sub.1 a.sub.3 t/cm which is in proportion to the product of the frequency f/m of a clock and the phase add amount n. The analog voltage and the ramp function voltage are compared by a comparator, which outputs a synchronization pulse when they agree with each other.
Claims7
A signal generator comprising:
- a phase accumulator for accumulating a phase add amount n upon each occurrence of a clock of a frequency f/m and for providing an output;
- a waveform memory, coupled to said phase accumulator, which is read out based on the output of said phase accumulator;
- a first digital-to-analog (D-A) converter, coupled to said waveform memory, for converting the output of said waveform memory into an analog signal;
- a difference circuit, coupled to said phase accumulator, which, when said phase accumulator yields a carry output, generates an analog voltage V.sub.1 =a.sub.2 (n-k.sub.s) which is in proportion to the difference between the output k.sub.s of the phase accumulator and the phase add amount n;
- a ramp function voltage generator for generating a ramp voltage V(t)=nfa.sub.1 a.sub.3 t/cm which is in proportion to the product of the clock frequency f/m and the phase add amount n;
- and
- a comparator, coupled to said ramp function voltage generator and said difference circuit, which compares the analog voltage and the ramp function voltage and outputs a synchronization pulse when they agree with each other.
A phase accumulation type signal generator for receiving a phase add amount and a clock, comprising:
- a phase accumulator for accumulating the phase add amount upon each occurrence of the clock and for providing an added output and a carry output;
- a waveform memory, coupled to said phase accumulator, for reading out data based on the added output of said phase accumulator;
- a difference circuit, coupled to said phase accumulator, for generating an analog voltage proportional to the difference between the added output of said phase accumulator and the phase add amount when said phase accumulator yields the carry output;
- a ramp function voltage generator for generating a ramp voltage which is in proportion to the product of the clock frequency and the phase add amount;
- and
- a comparator, coupled to said ramp function voltage generator and said difference circuit, for comparing the ramp voltage and the analog voltage, and for generating a synchronization pulse when the analog voltage and the ramp function voltage are substantially equal to each other.
Dependencies are inferred from the claim text.