# US 2024/0202151 A1 · Hybrid transmitter with calibration

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- Number: US 2024/0202151 A1
- Document ID: US20240202151A1
- Status: Published application
- Kind: A1
- Application number: 18/081,631
- Filed: 2022-12-14
- Published: 2024-06-20
- Earliest claimed: 2022-12-14
- Assignees: QUALCOMM Incorporated
- Applicants: QUALCOMM Incorporated
- Inventors: Changkyo LEE; Ashwin SETHURAM
- Web page: https://patentgrep.com/patent/US20240202151A1

## CPC

- G06F 13/38: Information transfer, e.g. on bus (G06F13/14 takes precedence)
- H03K 19/0005: {Modifications of input or output impedance}
- H03K 17/6871: {the output circuit comprising more than one controlled field-effect transistor}
- H03K 19/017545: {Coupling arrangements; Impedance matching circuits}
- G06F 2213/40: Bus coupling
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)

## Abstract

A transmitter includes a pull-down circuit coupled between an output of the transmitter and a first rail, a first pull-up circuit coupled between a second rail and the output of the transmitter, and a second pull-up circuit coupled between the second rail and the output of the transmitter. The transmitter also includes a control circuit coupled to a control input of the first pull-up circuit and a control input of the second pull-up circuit. The control circuit is configured to output a first control signal to the control input of the first pull-up circuit, wherein the first control signal controls a drive strength of the first pull-up circuit. The control circuit is also configured to output a second control signal to the control input of the second pull-up circuit, wherein the second control signal controls a drive strength of the second pull-up circuit.

## Claims

### Claim 1

A system, comprising:
a transmitter, wherein the transmitter comprises:
a pull-down circuit coupled between an output of the transmitter and a first rail, wherein the pull-down circuit has a signal input coupled to a first input of the transmitter;
a first pull-up circuit coupled between a second rail and the output of the transmitter, wherein the first pull-up circuit has a signal input coupled to a second input of the transmitter;
a second pull-up circuit coupled between the second rail and the output of the transmitter, wherein the second pull-up circuit has a signal input coupled to the first input of the transmitter; and
a control circuit coupled to a control input of the first pull-up circuit and a control input of the second pull-up circuit, wherein the control circuit is configured to:
output a first control signal to the control input of the first pull-up circuit, wherein the first control signal controls a drive strength of the first pull-up circuit, and
output a second control signal to the control input of the second pull-up circuit, wherein the second control signal controls a drive strength of the second pull-up circuit.

### Claim 2 (depends on 1)

The system of claim 1, wherein the second rail is at a higher potential than the first rail.

### Claim 3 (depends on 1)

The system of claim 1, wherein the first pull-up circuit comprises:
n-type field effect transistors (NFETs), wherein a gate of each one of the NFETs is coupled to the second input of the transmitter; and
first switches, wherein each one of the first switches is coupled in series with a respective one of the NFETs between the second rail and the output of the transmitter, and on/off states of the first switches are controlled by the first control signal.

### Claim 4 (depends on 3)

The system of claim 3, wherein the second pull-up circuit comprises:
p-type field effect transistors (PFETs), wherein a gate of each one of the PFETs is coupled to the first input of the transmitter; and
second switches, wherein each one of the second switches is coupled in series with a respective one of the PFETs between the second rail and the output of the transmitter, and on/off states of the second switches are controlled by the second control signal.

### Claim 5 (depends on 4)

The system of claim 4, wherein:
the first control signal comprises a first digital code; and
the second control signal comprises a second digital code.

### Claim 6 (depends on 1)

The system of claim 1, further comprising a pre-drive circuit having a first output coupled to the first input of the transmitter, and a second output coupled to the second input of the transmitter, wherein the pre-drive circuit is configured to:
output a pre-drive signal at the first output of the pre-drive circuit; and
output a complement of the pre-drive signal at the second output of the pre-drive circuit.

### Claim 7 (depends on 6)

The system of claim 6, wherein the pre-drive circuit is coupled to a third rail having a first supply voltage, and the second rail has a second supply voltage.

### Claim 8 (depends on 7)

The system of claim 7, further comprising a voltage circuit configured to scale the first supply voltage based on a frequency of the pre-drive signal.

### Claim 9 (depends on 8)

The system of claim 8, wherein the control circuit is configured to:
set the first control signal to a first value and set the second control signal to a second value when the first supply voltage is at a first voltage level; and
set the first control signal to a third value and set the second control signal to a fourth value when the first supply voltage is at a second voltage level.

### Claim 10 (depends on 6)

The system of claim 6, wherein:
the first pull-up circuit is configured to pull up the output of the transmitter when the complement of the pre-drive signal is high; and
the second pull-up circuit is configured to pull up the output of the transmitter when the pre-drive signal is low.

### Claim 11 (depends on 10)

The system of claim 10, wherein the pull-down circuit is configured to pull down the output of the transmitter when the pre-drive signal is high.

### Claim 12

A method of calibration using a calibration circuit including a first pull-up circuit and a second pull-up circuit, wherein each one of the first pull-up circuit and the second pull-up circuit is configured to pull up an output node, the method comprising:
setting a signal input of the first pull-up circuit to one of multiple voltage levels;
sweeping a first control signal, wherein the first control signal controls a drive strength of the first pull-up circuit;
comparing a voltage at the output node with a target voltage using a comparator;
if an output of the comparator toggles, then determining a value of the first control signal at which the output of the comparator toggles; and
if the first control signal reaches a threshold value without the output of the comparator toggling, then calibrating a second control signal, wherein the second control signal controls a drive strength of the second pull-up circuit.

### Claim 13 (depends on 12)

The method of claim 12, wherein the target voltage corresponds to an output high voltage defined by a standard.

### Claim 14 (depends on 12)

The method of claim 12, wherein the threshold value is a maximum value of the first control signal.

### Claim 15 (depends on 12)

The method of claim 12, wherein the first pull-up circuit is coupled between a supply rail and the output node, and the target voltage is approximately equal to half a supply voltage of the supply rail.

### Claim 16 (depends on 12)

The method of claim 12, wherein sweeping the first control signal comprises sweeping the first control signal in a direction of increasing the drive strength of the first pull-up circuit.

### Claim 17 (depends on 12)

The method of claim 12, wherein calibrating the second control signal comprises:
sweeping the second control signal;
comparing the voltage at the output node with the target voltage using the comparator; and
determining a value of the second control signal at which the output of the comparator toggles.

### Claim 18 (depends on 17)

The method of claim 17, wherein the first control signal comprises a first digital code, and the second control signal comprises a second digital code.

### Claim 19 (depends on 18)

The method of claim 18, wherein:
sweeping the first control signal comprises sequentially changing the first digital code, and
sweeping the second control signal comprises sequentially changing the second digital code.

### Claim 20 (depends on 17)

The method of claim 17, wherein a signal input of the second pull-up circuit is set to a voltage level that is lower than each one of the multiple voltage levels.

### Claim 21 (depends on 17)

The method of claim 17, wherein the signal input of the second pull-up circuit is coupled to a ground.

### Claim 22 (depends on 17)

The method of claim 17, wherein:
the first pull-up circuit comprises n-type field effect transistors (NFETs) for pulling up the output node; and
the first control signal controls the drive strength of the first pull-up circuit by controlling which ones of the NFETs are enabled.

### Claim 23 (depends on 22)

The method of claim 22, wherein:
the second pull-up circuit comprises p-type field effect transistors (PFETs) for pulling up the output node; and
the second control signal controls the drive strength of the second pull-up circuit by controlling which ones of the PFETs are enabled.

### Claim 24 (depends on 12)

The method of claim 12, wherein the calibration circuit further includes a pull-down circuit and a resistor coupled in series between a first rail and a second rail, and the method further comprises:
sweeping a third control signal, wherein the third control signal controls a drive strength of the pull-down circuit;
comparing a voltage at the node between the pull-down circuit and resistor with the target voltage using comparator; and
determining a value of the third control signal at which the output of the comparator toggles.

### Claim 25 (depends on 24)

The method of claim 24, wherein the target voltage is approximately equal to half a supply voltage of the first rail.

### Claim 26 (depends on 25)

The method of claim 25, wherein the second rail is coupled to a ground.