Common mode shifting of single-ended signals based on linearity analysis
A first circuit receives a single-ended signal and a reference voltage. The first circuit shifts a common mode of the single-ended signal based on a level-shifting current. A preamplifier receives the single-ended signal and the reference voltage from the first circuit and amplifies the single-ended signal to obtain an amplified signal. A decision feedback equalizer (DFE) system receives the amplified signal and the reference voltage from the preamplifier. The DFE system generates a first average signal height of the amplified signal above the reference voltage and a second average signal height of the amplified signal below the reference voltage. A second circuit provides the level-shifting current to the first circuit and adjusts the level-shifting current based on a linearity parameter associated with the amplified signal.
1 . A receiver comprising:
a first circuit to receive a single-ended signal and a reference voltage and to shift a common mode of the single-ended signal based on a level-shifting current;
a preamplifier coupled to receive the single-ended signal and the reference voltage from the first circuit and to amplify the single-ended signal to obtain an amplified signal;
a decision feedback equalizer (DFE) system coupled to receive the amplified signal and the reference voltage from the preamplifier and to generate a first average signal height of the amplified signal above the reference voltage and a second average signal height of the amplified signal below the reference voltage; and
a second circuit coupled to provide the level-shifting current to the first circuit, the second circuit to adjust the level-shifting current based on a linearity parameter associated with the amplified signal.
2 . The receiver of claim 1 , further comprising logic coupled between the DFE system and the second circuit, wherein the logic is to:
receive, from the DFE system, the first average signal height;
receive, from the DFE system, the second average signal height;
determine a difference between the first average signal height and the second average signal height, wherein the linearity parameter depends on the difference; and
responsive to determining the difference between the first average signal height and the second average signal height is greater than a threshold criterion, provide an indication to the second circuit to adjust a first value of the level-shifting current to a second value of the level-shifting current.
3 . The receiver of claim 2 , wherein the logic comprising a finite state machine (FSM).
4 . The receiver of claim 1 , wherein the first circuit is further to level shift the reference voltage based on the level-shifting current.
5 . The receiver of claim 4 , wherein the first circuit comprising a first linear equalization circuit to level-shift the common mode of the single-ended signal and a second linear equalization circuit to level-shift the reference voltage, wherein the first linear equalization circuit and second linear equalization circuit are the same circuit.
6 . The receiver of claim 1 , wherein the first circuit is further to attenuate at least one of the single-ended signal or the reference voltage to be within an operating range of the preamplifier.
7 . The receiver of claim 1 , wherein the preamplifier is a differential amplifier and the amplified signal is a differential signal.
8 . The receiver of claim 1 , wherein the receiver is located within a dynamic random access memory (DRAM) or within a processing device.
9 . An integrated circuit comprising:
a first circuit to receive a single-ended signal and a reference voltage and to shift a common mode of the single-ended signal and the reference voltage based on a level-shifting current; and
a second circuit coupled to provide the level-shifting current to the first circuit, the second circuit to adjust the level-shifting current based on a linearity parameter.
10 . The integrated circuit of claim 9 , further comprising:
a preamplifier coupled to receive the single-ended signal and the reference voltage from the first circuit and to amplify the single-ended signal to obtain an amplified signal, wherein the linearity parameter is associated with the amplified signal; and
a decision feedback equalizer (DFE) system coupled to receive the amplified signal and the reference voltage from the preamplifier and to generate a first average signal height of the amplified signal above the reference voltage and a second average signal height of the amplified signal below the reference voltage.
11 . The integrated circuit of claim 10 , further comprising logic coupled between the DFE system and the second circuit, wherein the logic is to:
receive, from the DFE system, the first average signal height;
receive, from the DFE system, the second average signal height;
determine a difference between the first average signal height and the second average signal height, wherein the linearity parameter depends on the difference; and
responsive to determining the difference between the first average signal height and the second average signal height is greater than a threshold criterion, provide an indication to the second circuit to adjust a first value of the level-shifting current to a second value of the level-shifting current.
12 . The integrated circuit of claim 10 , wherein the first circuit is further to attenuate at least one of the single-ended signal or the reference voltage to be within an operating range of the preamplifier.
13 . The integrated circuit of claim 9 , wherein the first circuit is further to level shift the reference voltage based on the level-shifting current.
14 . The integrated circuit of claim 13 , wherein the first circuit comprising a first linear equalization circuit to level-shift the common mode of the single-ended signal and a second linear equalization circuit to level-shift the reference voltage, wherein the first linear equalization circuit and second linear equalization circuit are the same circuit.
15 . The integrated circuit of claim 10 , wherein the preamplifier is a differential amplifier and the amplified signal is a differential signal.
16 . A method of adjusting a single-ended signal of a receiver, the method comprising:
receiving the single-ended signal and a reference voltage;
amplifying the single-ended to obtain an amplified signal;
adjusting a level-shifting current based on a linearity parameter associated with the amplified signal; and
shifting a common mode of the single-ended signal based on the level-shifting current.
17 . The method of claim 16 , further comprising:
determining a first average signal height of the amplified signal below the reference voltage;
determining a second average signal height of the amplified signal above the reference voltage;
determining a difference between the first average signal height and the second average signal height, wherein the linearity parameter depends on the difference; and
responsive to determining the difference between the first average signal height and the second average signal height is greater than a threshold criterion, adjusting a first value of the level-shifting current to a second value of the level-shifting current.
18 . The method of claim 16 , further comprising shifting the reference voltage based on the level-shifting current.
19 . The method of claim 16 , further comprising attenuating at least one of the single-ended signal or the reference voltage to be within an operating range of a preamplifier associated with the receiver.
20 . The method of claim 16 , wherein the receiver is located within a dynamic random access memory (DRAM) or within a processing device.