Hyun-Bae Lee

A Serpentine Guard Trace to Reduce the Far-End Crosstalk Voltage and the Crosstalk Induced Timing Jitter of Parallel Microstrip Lines

A serpentine guard trace is proposed to reduce the peak far-end crosstalk voltage and the crosstalk induced timing jitter of parallel microstrip lines on printed circuit boards. The vertical sections of the serpentine guard increase the mutual capacitance without much changing the mutual inductance between the aggressor and victim lines. This reduces the difference between the capacitive and inductive couplings and hence the far-end crosstalk. Comparison with the no guard, the conventional guard, and the via-stitch guard shows that the serpentine guard gives the smallest values in both the peak far-end crosstalk voltage and the timing jitter. The time domain reflectometer (TDR) measurement shows that the peak far-end crosstalk voltage of serpentine guard is reduced to 44% of that of no guard. The eye diagram measurement of pseudo random binary sequence (PRBS) data shows that the timing jitter is also reduced to 40% of that of no guard.

A three-data differential signaling over four conductors with pre-emphasis and equalization: a CMOS current mode implementation

A current-mode differential signaling of three data over two pairs of transmission lines increases the effective maximum data rate per pair of transmission lines by about 37% over the conventional pure differential signaling. Each of two data is transmitted as a half-swing differential signal over a pair of transmission lines. The third data is transmitted as a half-swing complementary common-mode signal of the two pairs of transmission lines. Both a single-tap pre-emphasis and a single-tap decision feedback equalizer are combined with this work. Adding a D flip-flop between the equalizer amplifier and the MUX embedded D flip-flop of receiver enables 4-Gb/s operation of receiver. The chip fabricated by using a 0.25-/spl mu/m CMOS process shows the maximum data rates of 4 and 3.2 Gb/s over 20- and 60-cm-long FR4 transmission lines, respectively, with bit-error rate below 1E-12.

Serpentine Guard Trace to Reduce Far-end Crosstalk and Even-Odd Mode Velocity Mismatch of Microstrip Lines by More than 40%

A serpentine guard trace located between two microstrip transmission lines reduced the peak far-end crosstalk voltage and the difference in propagation delay times between the even and odd mode signals by more than half of those of the no guard case, respectively, without the PCB area overhead. This reduction was achieved by increasing mutual capacitance without changing mutual inductance.

A Delay Locked Loop With a Feedback Edge Combiner of Duty-Cycle Corrector With a 20%–80% Input Duty Cycle for SDRAMs

A feedback edge combiner is proposed for the duty-cycle corrector (DCC) of a delay locked loop (DLL) to increase the range of allowed input duty cycle. The feedback edge combiner generates the rising edge of a DCC output at the rising edge of an input clock. It generates the falling edge of the DCC output at the rising edge of a feedback clock that is a half-period-delayed signal of the DCC output. A dual-delay-line digitally controlled delay line (DCDL) is used for seamless boundary switching. The chip area of the DCDL is reduced by around 46% by employing the architecture of two short coarse delay lines followed by a fine phase mixer (FPM) and a long coarse delay line in series instead of the architecture of two long coarse delay lines followed by an FPM. The measurements on the chip fabricated in the 65-nm CMOS show the allowed input duty cycle in the range from 20% to 80%; root-mean-square and peak-to-peak jitters of 2.69 and 14.0 ps, respectively, at 2 GHz and 1.2 V; and the operating frequency range from 0.12 to 2.0 GHz at 1.2 V. The measured power consumption is 3.3 mW/GHz at 1.2 V. The chip area is 0.059 mm 2.

A 16.8 Gbps/Channel Single-Ended Transceiver in 65 nm CMOS for SiP-Based DRAM Interface on Si-Carrier Channel

A 16.8 Gbps/channel single-ended transceiver for SiP-based DRAM interface on silicon carrier channel is proposed in this paper. A transmitter, receiver, and channel are all included in a single package as SiP. A current mode 4:1 MUX with 1-tap feed-forward equalizer (FFE) is used as a serializer, and this 4:1 MUX uses 25% duty clock to prevent short circuit current when consecutive 2-phase clocks overlap. Additionally, an open drain output driver with asynchronous type 1-tap FFE is used in the transmitter. Because of its small physical size, a common mode variation of Si-carrier channel from process variation is more serious than that of conventional PCB. This common mode variation degrades bit error rates (BER) at single-ended signaling. To obtain effective single-ended signaling on Si-carrier channel, a source follower-based continuous time linear equalizers and self- VREF generator with training algorithm on the receiver are proposed. An implemented Si-carrier channel uses meshed layer as a reference to reduce insertion loss. A BER less than 1e-12 is achieved in 65 nm CMOS and the power efficiency of the transceiver is 5.9 pJ/bit with 120 Ω terminations at each transceiver side.

A 27% reduction in transceiver power for single-ended point-to-point DRAM interface with the termination resistance of 4×Z 0 at both TX and RX

The transceiver power is reduced by 27% in the single-ended point-to-point DRAM interface by increasing the termination resistance to 4×Z0 at both ends of TX and RX. The resultant increase of ISI and reflection is compensated for at RX by using the 1-tap and 2-tap integrating decision-feedback equalizer (IDFE), respectively, where the reflection tap position and the tap coefficients are found automatically during the training mode. This improves the bathtub opening of a 4-inch FR4 channel from 20% to 62.5% at 5Gb/s in 0.13μm CMOS.

A 16.8Gbps/channel single-ended transceiver in 65nm CMOS for SiP based DRAM interface on Si-carrier channel

A 16.8Gbps/channel single ended transceiver for SiP based DRAM interface on silicon carrier channel is presented. A transmitter, receiver, and channel are all included in a single package. On the transmitter, 1 tap FFEs are used in 4:1 MUX and in output driver. On the receiver, source follower based CTLEs and self Vref generator are used for obtaining effective single ended signaling on Si-carrier channel. A BER that is less than 1e-12 is achieved in 65nm CMOS. The power efficiency of the transceiver is 5.9pJ/bit with 120Ω terminations at each transceiver side.