Abstract

1. Gossipo-3: a test of a 1-ns TDC-per-pixel and an integrated Temp-sensor in a 0.13um CMOS technology Christoph Brezina2, Klaus Desch2 , Harry van der Graaf 1, Vladimir Gromov 1, Ruud Kluit 1, Andre Kruth2 1National Institute for Subatomic Physics (Nikhef), 1098 XG Amsterdam, the Netherlands, 2Institute of Physics, Bonn University, D-53115, Germany. Abstract In a joint effort of Nikhef (Amsterdam) and University of Bonn, the Gossipo-3 MPW test chip is being developed in which preamp-shaper-discriminator circuitry is being evaluated, as well as the performance of a low-power TDC-per-pixel circuit with a resolution of 1 ns. In another development, an on-chip temperature sensor is being designed, as an evolution of the previously realized CMOS bandgap reference. Micro-Pattern Gas Detectors : the read-out Gossipo-3: MPW prototype • Features • each pixel measures: • - hit arrival time → cluster’s drift time • time-over-threshold → charge deposit • triggering options: • external common stop • self-triggering (fast OR → common stop) • read-out options: • serial read-out of all the pixels • other functionalities: • - on-pixel memory (one event deep) • auto clear (no stop signal after expected latency) • multi-hit flag • 4-bit Threshold DAC (in each pixel) • INGRID & pixel analog signal monitors Cathode (drift) plane Cluster1 Cluster2 1mm … 30cm Cluster3 Integrated Grid Front-end Readout Chip • Requirements: [1] • - high-dense pixel structure (55μm x 55μm) • high efficiency of detecting of single primary electrons • high resolution (1ns) and wide dynamic range (10us) TDC-per-pixel • a smart architecture of the pixels readout • low power consumption • - array: 32 x 32, 1024 pixels • active area: 1.76mm x 1.76mm • terminating. (empty) pixels: • 4 rows (columns) • -chip size: 3.5 x 3.9 mm (13.6mm2) • - serial readout & configuration On-pixel fast oscillator 0ns…Tslow (25 ns) EN OUT Tfast (1.8 ns) NAND EN Gossipo-3: the pixel OUT Delay = Tfast/2 = Function (Temp, Vdd) 0…15 (4-bit TDC) Block diagram VDD effect Temp effect Local fast oscillator (600MHz) 4 bit Fast counter Tfast ,ns Tfast ,ns 2% / 10 ◦C • Main specifications • front-end: • - input parasitic capacitance < 10 fF • input noise σ ≈ 70 e- • - threshold ≈ 350 e- • - fast response ≈ 10ns (rise-time) • drift time measurements: • - event clock 40MHz • accuracy (bin size) 1.8ns (4-bit @ 25ns) • range 6.4μs (8-bit @ 25ns) • ToT measurements: • accuracy 25ns • range 400ns (4-bit @ 25ns) • data read-out : • 5-bit bus • total read-out time 100us • power consumption: • - goal →100mW/cm2 (3μW/pixel) 4 bit ToT counter - 12% / 100mV • Count/shift (data taking) • or • LFSR/shift (data read-out) Preamp Discr. control pad Channel-to-channel statistical spread is 4% 8 bit Slow counter Threshold -Test -Mask Temperature, ◦C Power supply voltage, Volts Thr DAC • Bus control signals • Clock • TRIGGER (common stop) • Read • RESET 1-4 bit ovfl. ∆ VDD < 50 mV ∆ TEMP < 30◦ C accumulated error < 6% (1.8 ns or 1 TDC) 6 bit Pixel configuration On-chip Temperature Sensor [2] Time diagrams Preamp • Motivations: • monitoring of the local temperature in large volume detectors • could be used to control detector cooling systems and improve safety Hit (asynchronous) ToT Clock Counter Fast Iref Counter ToT reset (once per sample) Trigger bit stream ~ Itemp / Iref 60pF Counter Slow Comp Counter Itemp D Q data Token Threshold Reset Clk (25kHz) Data read-out Phase (LFSR = Shift Registers) Data taking phase (LFSR = Counter) Σ∆ analog-to-digital converter A Radiation Hard Bandgap Reference Circuit (featuring DTMOST’s) [3] • Main specifications • - accuracy: ± 1 °C • range: -40 °C….. +100 °C • bandwidth: 50 samples/sec Plans Phase1: . a small-size (1mm2) MPW prototype chip: individual basic circuits (preamplifier, discriminator, local oscillator, TDC) . tape-out: July 11, 2009 Phase2 : . a large-size (13.6mm2) MPW prototype chip: 32x32 pixels array with required periphery circuits. . tape-out: November 9, 2009 References: [1] V.Gromov, R.Kluit, H. van derGraaf ”Development of a Front-end Pixel chip for Readout of Micro-Pattern Gas Detectors” Proceeding of Topical Workshop on Electronics for Particle Physics (TWEPP-08), pp.76-79, Naxos, Greece, September 2008. [2] A. Bakker and J.H.Huijsing “Micropower CMOS Temperature Sensor with Digital Output”, IEEE Journal of Solid-State Circuits, Vol.31, No7, July 1996. [3] V.Gromov, A.J. Annema, R. Kluit et al., “A Radiation Hard Bandgap Reference Circuit in a Standard 0.13um CMOS Technology,” IEEE Transactions on Nuclear Science, vol.54, issue 6, pp. 2727-2733, Dec. 2007.