* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Kondratenko_S.V.2
Integrated circuit wikipedia , lookup
Power electronics wikipedia , lookup
Analog television wikipedia , lookup
Schmitt trigger wikipedia , lookup
Electronic engineering wikipedia , lookup
Telecommunication wikipedia , lookup
Phase-locked loop wikipedia , lookup
Operational amplifier wikipedia , lookup
Oscilloscope history wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Loudspeaker wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Audio crossover wikipedia , lookup
Transistor–transistor logic wikipedia , lookup
Analog-to-digital converter wikipedia , lookup
Index of electronics articles wikipedia , lookup
Radio transmitter design wikipedia , lookup
Rectiverter wikipedia , lookup
Two-port network wikipedia , lookup
Analysis of noise immunity at common circuits of the front end parts of high-speed transceivers S.V. Kondratenko NRNU MEPhI ICPPA-2016, 14.10.2016 2 Plan • The proposed system of parameters of drivers noise immunity • Comparing of different drivers types at noise immunity • The simulation results of test examples • Conclusions ICPPA-2016, 14.10.2016 3 Investigated objects Alternative names of analog (A) blocks of the transceivers: ... interface (or front end) parts ... peripheral parts ... i/o buffers. Next, use the term “analog”. The focus is on the analog parts of the transmitters (drivers) due to large pulse current in their output stages, and increased sensitivity to the parasitic inductance in the common circuits (power and ground circuits). ICPPA-2016, 14.10.2016 4 The problem of noise immunity in the drivers • Opened keys are connected to the outputs of noisy power and ground buses, leading to a collapse of the eye. •Internal noises Un.int are correlated with the transmitted signal unlike interference received from the digital part of the transmitter Un.ext . The stylized eye diagrams for DTX = TXP-TXN output considering the influence of noises at common circuits VML driver •The blur of eye diagrams increases due to the influence of parasitic RLC elements of package pins and parasitic capacitors CP on the outputs. • Through current iTHR is grounded in different ways on HF, in general, the noises on common circuits are not in phase and are not suppressed completely in the load. ICPPA-2016, 14.10.2016 5 The proposed system of noise immunity parameters of the drivers • Standard for OpAmp parameter PSRR (Power Supply Rejection Ratio) is analogous to the K1,3-4 coefficient, but in general the proposed system of parameters describes the noise immunity of drivers for different values of parasitic elements more fully and accurately . •You can directly compare the parameters Zii, Kij for different drivers to assess their general noise immunity at common circuits. • Model parameters are calculated and analyzed in the frequency domain (ac), which simplifies findings and speeds up calculations. Input nodes 1 2 1 2 Z11 - Input impedance neglecting influence Output nodes 3 4 3-4 K13 K14 K1,3-4 neglecting influence TC for a single signal TC for a single signal TC for a differ. signal Z22 K23 K24 K2,3-4 TC for a single signal TC for a differ. signal input TC for a single impedance signal TC –transfer coefficient ICPPA-2016, 14.10.2016 6 Compared types of drivers Principle of operation: switching to the load reference... voltage current VML nVML Conditions of the equivalence: general Pseudo-LVDS (simplified) CML identical dimensions of the transistors at outputs (for LVDS-driver - after scaling) the same load resistance RL = 100 ohms the same own output impedance of 100 ohms ... and private (for numerical simulation) 0.18 micron CMOS technology target 800 mV swing of differential output signal (for drivers operating in voltage mode sweep vdd/2) the same parasitic elements (CP = 5 pF, L = 2 ... 5 nH at common circuits). ICPPA-2016, 14.10.2016 7 Calculated values of the parameters of noise immunity for compared drivers Pseudo-LVDS at vin={1,0}, changes Input nodes 1 2 nVML Input nodes 1 2 CML Input nodes 1 2 1 260 Ohm - 1 4,2 kOhm - 1 43 Ohm - at vin={0,1} 2 260 Ohm Output nodes 3 0,49 0,70 4 0,30 0,51 3-4 0,19 0,21 2 213 Ohm Output nodes 3 0,01 0,34 4 0,03 0,81 3-4 0,02 0,47 2 43 Ohm Output nodes 3 0,79 0,19 4 0,45 0,54 3-4 0,34 0,35 2 200 Ohm Output nodes 3 0,70 0,28 4 0,23 0,78 3-4 0,47 0,50 VML Input nodes 1 2 1 213 Ohm - ICPPA-2016, 14.10.2016 8 Findings of the analysis and calculations of the drivers According circuitry - only LVDS-driver output signal levels are not adhered to one or both of the common buses, which increases noise immunity. According output impedance - CML-driver has the lowest impedance (43 ohms in this case), which should increase the impact of noise on general circuits due to the prevailing inductive reaction of the impedance of power and ground pins. According transfer coefficients - the smallest differential noise transfer coefficient has LVDS-driver, the greatest - VML-driver. The tabulated values of the asymptotic impedances and transfer coefficients in fact depends on the frequency (decrease on HF), which may change the comparison results. ICPPA-2016, 14.10.2016 9 Simulated circuit of the TX-RX path and conditions of the simulation Conditions of the simulation: - at the input - a random 8b10b encoded signal at a rate of 1.25 Gbps (1X) - normal conditions PVT - for the CML, VML and nVML drivers the same type of receivers are used, for the pseudo-LVDS driver - differed receiver with the power supply 2.5 V for input stage. ICPPA-2016, 14.10.2016 10 Eye diagrams: 1,25 Gbps, TQFP-208 package RX inputs All TX-RX pairs are successfully working, but pseudo-LVDS driver is better RX outputs ICPPA-2016, 14.10.2016 11 Eye diagrams: 2,5 Gbps, TQFP-208 package • Drivers sequence in order of preference: VML (worst) nVML CML Pseudo-LVDS (best) • This is consistent with previous findings on the basis of parameters of noise immunity. ICPPA-2016, 14.10.2016 12 CONCLUSION 1. In the early stages of designing high-speed transceiver in serial channels it is advisable to take into account the effect of parasitic constructive elements in order to choose among alternative realizations of analog parts of the transmitter and receiver. 2. To evaluate the noise immunity of the analog parts on common circuits (power and ground) the system of parameters proposed including impedances of interested nodes and transmission coefficients on their driver outputs. This system includes a standard parameter PSRR, but in general it describes the noise immunity of drivers for different values of parasitic elements more fully and accurately. 3. Comparison of parameters of noise immunity for the four types of drivers showed the advantage of pseudo-LVDS drivers. This was confirmed in the simulation transmitter-receiver path, designed in 0.18 micron CMOS technology with regard parasitic package parameters such as TQFP-208 and running at speeds up to 2,5 Gbps. 4. Used system of noise immunity parameters forms a specialized macro model of the drivers to analyze their noise immunity on common circuits. In contrast to the IBIS-model parameters proposed linearized macro models are determined by calculation or analysis in the frequency domain, less labor-intensive than calculations or analysis in the time domain. ICPPA-2016, 14.10.2016 Thank you for attention! ICPPA-2016, 14.10.2016