Patent US6504397B1 successfully refreshed from Google Patents.
US6504397B1
Expired / Lapsed
US
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Output controlled line driver with programmable common mode control
Assignee: MOBILITY SEMICONDUCTOR Inc
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Filing: 2001-09-07
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Granted: 2003-01-07
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Expires: 2021-09-07
Abstract
Abstract A differential line driver having integrated output termination resistors is disclosed. The termination resistors are a combination of a controlled transistor and a low precision resistor. The transistor calibrates-out the imprecision of the resistor based on a precise electrical reference. In a preferred embodiment the transistor is a CMOS transistor and the resistor is a CMOS resistor. The combination of a CMOS transistor and CMOS resistor features higher linearity and precision than a CMOS transistor alone due to the smaller effective drain-source voltage across the CMOS transistor. Moreover, the present invention discloses independent programmability of the integrated output termination resistor, the output common mode voltage, and the output amplitude. The value of the output termination resistor(s), the value of the output common mode voltage, and the value of the output amplitude are controlled independently and are continuously maintained with respect to a precise electrical reference. As a result, the value of the output termination resistance, the value of the output common mode voltage, and the value of the output amplitude are insensitive to manufacturing process tolerances and variations in temperature and supply voltage.
Inventors
- 👤 Siegfried Hart
- 👤 Palaksha Setty
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:49
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/16; H04; H04L; H04L25/00; H04L25/02; H04L25/0264; H04L25/028; H04L25/0272; H04L25/0276; H04L25/0278
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
210 words
A line driver device for providing an independently controllable output termination resistance, an output amplitude, and an output common mode, the device comprising: a first programmable current mirror for multiplying a fixed reference current to achieve a first predetermined current; a fixed current mirror for sourcing the first predetermined current; an adjustable termination resistor connected to the fixed current mirror to receive the first predetermined current; an error amplifier in communication with the adjustable termination resistor for sensing a termination resistor voltage across the adjustable termination resistor and comparing the termination resistor voltage to a fixed reference voltage, whereby the amplifier provides an amplifier output signal to the adjustable termination resistor to cause the termination resistor voltage to match the fixed reference voltage; at least one adjustable output termination resistor in communication with the amplifier output signal; a second programmable current mirror for multiplying the first predetermined current to achieve a second predetermined current for defining a common mode voltage and an output voltage amplitude; and an output stage in communication with the second programmable current mirror and the at least one adjustable output termination resistor, the output stage having a plurality of voltage controlled switches for defining an output polarity and an output voltage amplitude of the line driver.
Claim 2
Dependent Claim
210 words
A line driver device for providing an independently controllable output termination resistance, an output amplitude, and an output common mode, the device comprising: a first programmable current mirror for multiplying a fixed reference current to achieve a first predetermined current; a fixed current mirror for sourcing the first predetermined current; an adjustable termination resistor connected to the fixed current mirror to receive the first predetermined current; an error amplifier in communication with the adjustable termination resistor for sensing a termination resistor voltage across the adjustable termination resistor and comparing the termination resistor voltage to a fixed reference voltage, whereby the amplifier provides an amplifier output signal to the adjustable termination resistor to cause the termination resistor voltage to match the fixed reference voltage; at least one adjustable output termination resistor in communication with the amplifier output signal; a second programmable current mirror for multiplying the first predetermined current to achieve a second predetermined current for defining a common mode voltage and an output voltage amplitude; and an output stage in communication with the second programmable current mirror and the at least one adjustable output termination resistor, the output stage having a plurality of voltage controlled switches for defining an output polarity and an output voltage amplitude of the line driver.
Claim 3
Dependent Claim
30 words
The line driver of claim 1 wherein the first programmable current mirror is capable of producing an output current that is n times an input current, wherein n is variable.
Claim 4
Dependent Claim
25 words
The line driver of claim 1 wherein the fixed current mirror receives an input current and outputs an output current equal to the input current.
Claim 5
Dependent Claim
30 words
The line driver of claim 1 wherein the second programmable current mirror is capable of producing an output current that is n times an input current, wherein n is variable.
Claim 6
Dependent Claim
15 words
The line driver of claim 1 wherein the output stage has two voltage controlled switches.
Claim 7
Dependent Claim
13 words
The line driver of claim 1 further comprising two adjustable output termination resistors.
Claim 8
Dependent Claim
15 words
The line driver of claim 1 wherein the adjustable termination resistor further comprises a transistor.
Claim 9
Dependent Claim
13 words
The line driver of claim 7 wherein the transistor is a CMOS transistor.
Claim 10
Dependent Claim
21 words
The line driver of claim 1 wherein the adjustable termination resistor further comprises a resistor and a transistor connected in series.
Claim 11
Dependent Claim
20 words
The line driver of claim 9 wherein the transistor is a CMOS transistor and the resistor is a CMOS resistor.
Claim 12
Independent Claim
202 words
A method for providing an independently controllable output termination resistance, output amplitude, and output common mode voltage in a line driver, the method comprising: multiplying a fixed reference current to achieve a first predetermined current using a first programmable current mirror; sourcing the first predetermined current using a fixed current mirror; receiving the first predetermined current at an adjustable termination resistor connected to the fixed current mirror; sensing a termination resistor voltage across the adjustable termination resistor using an error amplifier in communication with the adjustable termination resistor; comparing the termination resistor voltage to a fixed reference voltage, whereby the amplifier provides an amplifier output signal to the adjustable termination resistor to cause the termination resistor voltage to match the fixed reference voltage; multiplying the first predetermined current to achieve a second predetermined current for defining a common mode voltage and an output voltage amplitude using a second programmable current mirror; and providing an output polarity and an output voltage amplitude of the line driver using an output stage in communication with the second programmable current mirror and at least one adjustable output termination resistor in communication with the amplifier output signal, the output stage having a plurality of voltage controlled switches.
Claim 13
Independent Claim
202 words
A method for providing an independently controllable output termination resistance, output amplitude, and output common mode voltage in a line driver, the method comprising: multiplying a fixed reference current to achieve a first predetermined current using a first programmable current mirror; sourcing the first predetermined current using a fixed current mirror; receiving the first predetermined current at an adjustable termination resistor connected to the fixed current mirror; sensing a termination resistor voltage across the adjustable termination resistor using an error amplifier in communication with the adjustable termination resistor; comparing the termination resistor voltage to a fixed reference voltage, whereby the amplifier provides an amplifier output signal to the adjustable termination resistor to cause the termination resistor voltage to match the fixed reference voltage; multiplying the first predetermined current to achieve a second predetermined current for defining a common mode voltage and an output voltage amplitude using a second programmable current mirror; and providing an output polarity and an output voltage amplitude of the line driver using an output stage in communication with the second programmable current mirror and at least one adjustable output termination resistor in communication with the amplifier output signal, the output stage having a plurality of voltage controlled switches.
Claim 14
Dependent Claim
34 words
The method of claim 11 wherein multiplying a fixed reference current further comprises producing an output current that is n times a input current using the first programmable current mirror, wherein n is variable.
Claim 15
Dependent Claim
32 words
The method of claim 11 wherein sourcing the first predetermined current further comprises receiving an input current and outputting an output current equal to the input current using the fixed current mirror.
Claim 16
Dependent Claim
34 words
The method of claim 11 wherein multiplying the first predetermined current further comprises producing an output current that is n times an input current using the second programmable current mirror, wherein n is variable.
Claim 17
Dependent Claim
16 words
The method of claim 11 further comprising providing two voltage controlled switches in the output stage.
Claim 18
Dependent Claim
13 words
The method of claim 11 further comprising providing two adjustable output termination resistors.
Claim 19
Dependent Claim
21 words
The method of claim 11 further comprising providing a resistor and a transistor connected in series in the adjustable termination resistor.
Claim 20
Dependent Claim
22 words
The method of claim 17 wherein providing a resistor and a transistor further comprise providing a CMOS transistor and a CMOS resistor.
References Cited (Backward Citations)
US5581197A
Cited
US6054874A
Cited
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