Switchable PLL circuit
First Claim
1. An electronic circuit with a first PLL circuit including a first phase comparator and a first controllable oscillator, with a second PLL circuit including a second phase comparator and a second controllable oscillator, wherein an input signal is supplied to an input of the first PLL circuit, wherein the input signal or the output of the first PLL circuit is selectively supplied to an input of the second PLL circuit, and wherein the output of the second PLL circuit is the single output of the circuit.
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Accused Products
Abstract
An electronic circuit includes a first and a second PLL stage (PLL1, PLL2) that can be switched in parallel or in series depending on locking of the first one of the PLL circuits to an input signal (IN). When in parallel, only the second PLL circuit (PLL2) is actively supplying a clock signal to the output of the electronic circuit. The first PLL circuit (PLL1) continues trying to lock onto the input signal (IN). A lock detector (LD) monitors the locking status of the first PLL circuit (PLL1) to the input signal (IN) and, upon locking, sets switches (S1, S2) to couple the output of the first PLL circuit (PLL1) to the input of the second PLL circuit (PLL2), and to couple the output of the second PLL circuit (PLL2) to the input of the first PLL circuit (PLL1).
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Citations
10 Claims
- 1. An electronic circuit with a first PLL circuit including a first phase comparator and a first controllable oscillator, with a second PLL circuit including a second phase comparator and a second controllable oscillator, wherein an input signal is supplied to an input of the first PLL circuit, wherein the input signal or the output of the first PLL circuit is selectively supplied to an input of the second PLL circuit, and wherein the output of the second PLL circuit is the single output of the circuit.
Specification