# US 2022/0045702 A1 · Dc detector for a transmit datapath > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2022/0045702 A1 - Document ID: US20220045702A1 - Status: Published application - Kind: A1 - Application number: 17/382,910 - Filed: 2021-07-22 - Published: 2022-02-10 - Earliest claimed: 2020-08-07 - Assignees: Analog Devices, Inc. - Applicants: Analog Devices, Inc. - Inventors: Robert D. Solanki; Christopher Mayer - Web page: https://patentgrep.com/patent/US20220045702A1 ## CPC - H04B 1/04: Circuits - H04B 2001/045: {with means for improving efficiency} - H04B: TRANSMISSION ## Abstract A transmitter with a DC detection circuit that can control when a modulator of the transmitter is active. When data is being transmitted, a tone introduced by a mixer in the transmit path is hidden by the data signal and has minimal effect on the transmit path. However, when there is no data, the tone can cause undesirable noise. A modulator may move the tone or noise outside of the transmitter's bandwidth. As the data can hide the tone, the DSM may only be needed when there is a DC signal. By activating the DSM only when a DC signal is detected, the extra power introduced by the modulator can be reduced while eliminating in-band noise. ## Claims ### Claim 1 A transmitter comprising: a filter chain configured to process a transmit signal; a modulator configured to convert the transmit signal to a digital transmit signal when enabled; a digital-to-analog converter configured to convert the digital transmit signal to an analog signal; and a DC detector configured to determine a percentage of DC component within the transmit signal and to enable the modulator when the percentage of DC component satisfies a DC threshold. ### Claim 2 (depends on 1) The transmitter of claim 1, wherein the modulator is a delta-sigma modulator. ### Claim 3 (depends on 1) The transmitter of claim 1, wherein the DC detector is configured to determine a percentage of DC component within a sample window of the transmit signal. ### Claim 4 (depends on 1) The transmitter of claim 1, wherein the DC detector comprises a sample comparator configured to compare a first sample obtained from the transmit signal and a second sample obtained from the transmit signal. ### Claim 5 (depends on 4) The transmitter of claim 4, wherein the first sample and the second sample comprise successive samples in a series of samples obtained from the transmit signal. ### Claim 6 (depends on 4) The transmitter of claim 4, wherein the DC detector further comprises an accumulator configured to accumulate samples of the transmit signal corresponding to a sample window. ### Claim 7 (depends on 6) The transmitter of claim 6, wherein the accumulator comprises an infinite impulse response (IIR) aggregator. ### Claim 8 (depends on 6) The transmitter of claim 6, wherein the accumulator is further configured to determine a DC count, the DC count comprising a count of successive samples within a sample window that the DC detector determines are equal. ### Claim 9 (depends on 8) The transmitter of claim 8, wherein the accumulator is further configured to determine a percentage of DC within the sample window based at least in part on the DC count. ### Claim 10 (depends on 8) The transmitter of claim 8, wherein the DC detector further comprises a threshold comparator configured to: determine whether the DC count satisfies the DC threshold; and output an enable signal to enable the modulator when the DC count satisfies the DC threshold. ### Claim 11 A wireless device comprising: an antenna configured to transmit a radio frequency signal; and a transmitter configured to generate the radio frequency signal for transmission by the antenna, the transmitter comprising: a filter chain configured to process a transmit signal; a modulator configured to convert the transmit signal to a digital transmit signal when enabled; a digital-to-analog converter configured to convert the digital transmit signal to an analog signal; and a DC detector configured to determine a percentage of DC component within the transmit signal and to enable the modulator when the percentage of DC component satisfies a DC threshold. ### Claim 12 (depends on 11) The wireless device of claim 11, wherein the DC detector comprises a sample comparator configured to compare a first sample obtained from the transmit signal and a second sample obtained from the transmit signal, and wherein the first sample and the second sample comprise successive samples in a series of samples obtained from the transmit signal. ### Claim 13 (depends on 11) The wireless device of claim 11, wherein the DC detector comprises an accumulator configured to: accumulate samples of the transmit signal corresponding to a sample window; and determine a DC count, wherein the DC count comprises a count of successive samples within the sample window that the DC detector determines are equal. ### Claim 14 (depends on 13) The wireless device of claim 13, wherein the accumulator is further configured to determine a percentage of DC within the sample window based at least in part on the DC count. ### Claim 15 (depends on 13) The wireless device of claim 13, wherein the DC detector further comprises a threshold comparator configured to: determine whether the DC count satisfies the DC threshold; and output an enable signal to enable the modulator when the DC count satisfies the DC threshold. ### Claim 16 A method of reducing power consumption in a transmitter, the method comprising: by a DC detector implemented in hardware, receiving a first sample of a transmit signal within a sample window; receiving a second sample of a transmit signal within the sample window; determining whether the first sample and the second sample are the same; responsive to determining that the first sample and the second sample are the same, incrementing a DC count; determining whether the DC count satisfies a DC threshold; and responsive to determining that the DC count satisfies the DC threshold, enabling a modulator within a transmit path of the transmitter. ### Claim 17 (depends on 16) The method of claim 16, wherein, responsive to determining that the DC count does not satisfy the DC threshold, disabling the modulator. ### Claim 18 (depends on 16) The method of claim 16, wherein determining whether the first sample and the second sample are the same comprises determining that a difference between the first sample and the second sample does not exceed a threshold difference. ### Claim 19 (depends on 16) The method of claim 16, further comprising receiving one or more additional samples within the sample window, wherein determining whether the first sample and the second sample are the same comprises determining whether the first sample, the second sample, and the one or more additional samples are the same, and wherein the DC count is incremented responsive to determining that the first sample, the second sample, and the one or more additional samples are the same. ### Claim 20 (depends on 16) The method of claim 16, further comprising: receiving a third sample within the sample window; determining whether the second sample and the third sample are the same; and responsive to determining that the second sample and the third sample are the same, incrementing the DC count, wherein the second sample and the third sample are successive samples.