Filter-based lock-in circuits for PLL and fast system startup
DCFirst Claim
1. A filter-based lock-in circuit used in a system for reducing system startup time and system latency time, comprising:
- an upper transistor and a lower transistor connected in series between a power supply and ground having a shared terminal which becomes a single bidirectional node, wherein the shared terminal is defined by a junction between the upper transistor and the lower transistor;
a sensing inverter for sensing a voltage at the single bidirectional node and comparing it with an input transition voltage of the sensing inverter which causes an output of the sensing inverter to be centered at half the power supply voltage wherein an input terminal of the sensing inverter is connected to the single bidirectional node;
a logic gate coupled between an output terminal of the sensing inverter and a gate terminal of the upper transistor; and
wherein an initial voltage at the single bidirectional node of the filter-based lock-in circuit is almost the same as the input transition voltage of the sensing inverter.
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Abstract
All embodiments of the present invention basically include an upper transistor and a lower transistor connected in series between a power supply and ground. The upper transistor and the lower transistor have a shared source (or drain) terminal which becomes a single bidirectional node. They further comprise a sensing gate and a logic gate. The sensing inverter has a function of sensing a voltage at the single bidirectional node and comparing it with an input transition voltage since an input terminal of the sensing inverter is connected to the single bidirectional node. An initial voltage at the single bidirectional node of the filter-based lock-in circuit is almost the same as the input transition voltage of the sensing inverter, where the input transition voltage is an input voltage which causes an output voltage to be
Consequently, all embodiments of the present invention provide a fast lock-in time performance and achieve a drastic improvement in system startup time, system latency time, system simulation time, system test time, cost, and time to market
9 Citations
20 Claims
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1. A filter-based lock-in circuit used in a system for reducing system startup time and system latency time, comprising:
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an upper transistor and a lower transistor connected in series between a power supply and ground having a shared terminal which becomes a single bidirectional node, wherein the shared terminal is defined by a junction between the upper transistor and the lower transistor; a sensing inverter for sensing a voltage at the single bidirectional node and comparing it with an input transition voltage of the sensing inverter which causes an output of the sensing inverter to be centered at half the power supply voltage wherein an input terminal of the sensing inverter is connected to the single bidirectional node; a logic gate coupled between an output terminal of the sensing inverter and a gate terminal of the upper transistor; and wherein an initial voltage at the single bidirectional node of the filter-based lock-in circuit is almost the same as the input transition voltage of the sensing inverter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification