US 2014/0111248 A1 · LOW SUPPLY VOLTAGE ANALOG DISCONNECTION ENVELOPE DETECTOR

Abstract

An analog disconnection envelope detection circuit having a low power supply detects a high speed, high differential voltage disconnect state on a data line. Level-shifting circuitry shifts the voltage level of two input signals by the value of a detection threshold voltage, generates differential signals used to indicate conditions of the input signals, and mitigates effects of input differential signal common-mode voltage on the detection operation. Circuitry is provided to equalize VDS of detecting tail current sources, thereby eliminating errors resulting from VDS mismatch of tail current sources. Comparator circuitry compares the sets of differential signals and indicates when the absolute difference between the two input signals is greater than a reference voltage. Output circuitry generates a disconnect signal corresponding to the disconnect condition. When compared to conventional disconnect detection circuitry, the disclosed circuit utilizes a relatively low supply voltage to detect high differential voltage disconnect conditions with improved accuracy.

Claims21

Dependent claims

A disconnect detection circuit, comprising:

a first input transistor coupled to receive a first input signal;
a second input transistor coupled to receive a second input signal;
regulating circuitry operable to produce a regulated voltage for controlling a plurality of current sources to generate a first set of differential signals indicative of a disconnect condition, the plurality of current sources including a first source transistor and a second source transistor, wherein the second source transistor is coupled to the second input transistor;
a resistance coupled between the first source transistor and the first input transistor;
and
logic circuitry operable to process the first set of differential signals to generate a disconnect signal.

3 more elements

A disconnect detection circuit, comprising:

sensing circuitry operable to receive a first input signal and a second input signal, the sensing circuitry including a pair of first input transistors, each operable to receive the first input signal, and a pair of second input transistors, each operable to receive the second input signal;
current sourcing circuitry comprising a pair of first source transistors, each coupled to respective ones of the first input transistors, and a pair of second source transistors, each coupled to respective ones of the second input transistors;
regulating circuitry operable to produce a regulated voltage for controlling the current sourcing circuitry to generate a first set of differential signals indicative of a first disconnect condition and a second set of differential signals indicative of a second disconnect condition;
and
logic circuitry operable to process the first and second sets of differential signals to generate a disconnect signal.

2 more elements

Dependencies are inferred from the claim text.

Low supply voltage analog disconnection envelope detector

Life of this patent

Low supply voltage analog disconnection envelope detector

Life of this patent

Abstract

Claims21