Equalized multi-signaling mode driver
AssigneeRambus Inc.
InventorReza Navid
Life of this patent
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Abstract
A transmit circuit can be configured to output two-level pulse amplitude modulation (PAM-2) or four-level pulse amplitude modulation (PAM-4). In the PAM-2 mode, pre-tap feed-forward equalization (FFE) and post-tap FFE can be applied to the PAM-2 signal by pre-taps and post-taps, respectively. In the PAM-4 mode, at least one post-tap is repurposed to generate, along with the main tap, the main PAM-4 signaling levels. At least one PAM-2 FFE tap is repurposed to apply FFE in the PAM-4 mode.
Claims21
1-20. (canceled)
An integrated circuit, comprising:
- a data transmitter circuit having a multi-tap finite impulse response (FIR) equalizer including at least a main tap and at least one feed-forward equalization (FFE) tap;
- and,
- mode selection circuitry to, in a two-level pulse amplitude modulation (PAM-2) mode, configure the main tap to generate a PAM-2 data signal, and to configure the at least one FFE tap to apply FFE to the PAM-2 data signal, the mode selection circuitry also to, in a four-level pulse amplitude modulation (PAM-4) mode, configure the main tap and the at least one FFE tap to combine to generate a main PAM-4 data signal.
An integrated circuit having a transmitter that is selectively reconfigurable, the transmitter comprising:
- a main tap to drive a two-level pulse amplitude modulation (PAM-2) signal;
- a first tap to apply pre-tap feed-forward equalization (FFE) to said PAM-2 signal in a first selectable configuration of the transmitter;
- and,
- a second tap to apply post-tap FFE to said PAM-2 signal in said first selectable configuration of the transmitter, at least one of said first tap and said second tap are configurable in a second selectable configuration of the transmitter to drive a bit of a four-level pulse amplitude modulation (PAM-4) signal.
An integrated circuit, comprising:
- a configurable transmitter for selectively driving, with feed-forward equalization (FFE), at least one of a PAM-2 and a PAM-4 signal, comprising:
- a main tap to drive a PAM-2 signal in a first configuration and a first bit of a PAM-4 signal in a second configuration;
- and,
- at least one tap to apply one of pre-tap FFE or post-tap FFE in said first configuration and to drive a second bit of said PAM-4 signal in said second configuration.
Dependencies are inferred from the claim text.