Caravel Analog User

This is the first test chip from the Chipalooza challenge 2024. 11 designs made it on the April tapeout.

The projects on this tapeout and their source URLs are as follows:

1.      High-speed crystal oscillator (4-16MHz)
    hsxo-cpz1 
    https://github.com/efabless/sky130_ht_ip__hsxo_cpz1 (forked)
    https://github.com/htfab/hsxo-cpz1
    Tamas Hubai

2.      Brownout detector
    sky130_ajc_ip__brownout
    https://github.com/efabless/sky130_ajc_ip__brownout (forked)
    https://github.com/ajcci/sky130_ajc_ip__brownout
    Robin Tsang

3.      Overvoltage detector
    sky130_ajc_ip__overvoltage
    https://github.com/efabless/sky130_ajc_ip__overvoltage (forked)
    https://github.com/ajcci/sky130_ajc_ip__overvoltage
    Robin Tsang

4.      Power-on-Reset
    sky130_ajc_ip__por
    https://github.com/efabless/sky130_ajc_ip__por (forked)
    https://github.com/ajcci/sky130_ajc_ip__por
    Robin Tsang

5.      Comparator
    sky130_ak_ip__comparator
    https://github.com/efabless/sky130_ak_ip__comparator (forked)
    https://github.com/andrewkkang/sky130_ak_ip__comparator
    Andrew Kang

6.      Low-speed crystal oscillator (32kHz)
    sky130_be_ip__lsxo
    https://github.com/efabless/sky130_be_ip__lsxo (forked)
    https://github.com/b-etz/sky130_be_ip__lsxo
    Brady Etz

7.      Temperature sensor
    sky130_od_ip__tempsensor
    https://github.com/efabless/sky130_od_ip__tempsensor (forked)
    https://github.com/ordicker/sky130_od_ip__tempsensor
    Or Dicker

8.      Low power operational amplifier
    sky130_rodovalho_ip__lpopamp
    https://github.com/efabless/sky130_rodovalho_ip__lpopamp (forked)
    https://github.com/lhrodovalho/sky130_rodovalho_ip__lpopamp
    Luis Henrique Rodovalho

9.      High gain-bandwidth operational amplifier
    sky130_td_ip__opamp_hp
    https://github.com/efabless/sky130_td_ip__opamp_hp (forked)
    https://github.com/tdextrous/sky130_td_ip__opamp_hp
    Thomas Dexter

10.     Overvoltage detector
    sky130_vbl_ip__overvoltage
    https://github.com/efabless/sky130_vbl_ip__overvoltage (forked)
    https://github.com/LDFranck/sky130_vbl_ip__overvoltage
    Lucas Franck, William Orlato, and Toni Tejada

11. Bandgap (not from Chipalooza)
    bandgap
    https://github.com/efabless/sky130_cw_ip (forked)
    https://github.com/christoph-weiser/mpw7
    Christoph Weiser

12. Power FET (not from Chipalooza)
    power_stage
    (in this repository)
    Weston Braun

13. Bias current generator (not from Chipalooza)
    bias_generator
    (in this repository)
    Tim Edwards

14. Ground-isolated analog switch (not from Chipalooza)
    isolated_switch_ena1v8
    (in this repository)
    Tim Edwards

(Documentation, including test instructions, still needs to be completed)

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Building:

Get the dependencies above by doing "make get_ip_blocks" in the top level directory. This will clone all of the IP blocks from various github repository sources into the "dependencies" directory.

The test chip is generated in magic by running magic in the mag/ directory and issuing the command "source construct_testchip.tcl".

Verifying:

In the top level directory, do "make run-precheck". This requires at least setting environment variables PDK_ROOT, PDK, and PRECHECK_ROOT. If the PDK is installed with open_pdks, then PRECHECK_ROOT can be set to open_pdks/sources/precheck_sky130.

Testing:

All projects are connected either to the logic analyzer (128 I/O bits) or the GPIO pins. Generally speaking, static control bits (enable and trim, for example) are logic analyzer outputs. Dynamic digital bits are routed to GPIO digital outputs, while analog I/O are routed to the analog connections of the GPIO.

Each power supply is routed through gated power pFETs so each project can be powered individually. Each power supply connection internally is routed to a bare analog pin for monitoring the supply voltage of the project. Be aware that these are ESD-sensitive points!

Power supplies are enabled through a differential switch. Due to time constraints, the differential signals (enable, !enable) were both routed to the logic analyzer. Both bits need to be set correctly.

Most projects take current biases which are distributed by a central bias current generator circuit. Various test point bias currents are connected through ground-isolated switches to GPIO analog signals.

Project circuit blocks are described below, starting at the top left corner of the chip and working counterclockwise around the chip perimeter.

High Gain-Bandwidth Operational Amplifier (Thomas Dexter) Enable: la_data_out[37] Bias: 100nA when selected Selection: la_data_out[40] = 0 Upstream analog power supply: vdda2/vssa2 Upstream digital power supply: vccd2/vssd2 Power supply monitor: io_analog[10] Power supply enable: la_data_out[60] Power supply !enable: la_data_out[61] Amp output: gpio_noesd[7] Amp negative input: gpio_analog[8] when selected Selection: la_data_out[36] = 1 Amp positive input: gpio_analog[9] when selected Selection: la_data_out[34] = 1

Temperature sensor (Or Dicker) Enable: la_data_out[35] Bias: gpio_noesd[2] (nominally 1.2V) when selected Selection: la_data_out[122] = 1 Upstream digital power supply: vccd2/vssd2 Power supply monitor: io_analog[9] Power supply enable: la_data_out[58] Power supply !enable: la_data_out[59] Vbe1_out: gpio_analog[8] when selected Selection: la_data_out[36] = 0 Vbe2_out: gpio_analog[9] when selected Selection: la_data_out[34] = 0

Comparator (Andrew Kang) Enable: la_data_out[28] Hysteresis: la_data_out[29:30] Trim: la_data_out[25:27],la_data_out[33:31] Bias: 400nA when selected Selection: la_data_out[44] = 0 Upstream analog power supply: vdda2/vssa2 Upstream digital power supply: vccd2/vssd2 Power supply monitor: io_analog[8] Power supply enable: la_data_out[56] Power supply !enable: la_data_out[57] Comparator output: io_out[17] Comparator negative input: gpio_analog[12] when selected Selection: la_data_out[22] = 1 Comparator positive input: gpio_analog[11] when selected Selection: la_data_out[23] = 1

Low power operational amplifier (Luis Henrique Rodovalho) Enable: la_data_out[21] Bias: 10uA when selected Selection: la_data_out[46] = 0 Upstream analog power supply: vdda2/vssa2 Upstream digital power supply: vccd2/vssd2 Power supply monitor: io_analog[7] Power supply enable: la_data_out[54] Power supply !enable: la_data_out[55] Amplifier output: gpio_analog[13] Amplifier negative input: gpio_analog[11] when selected Selection: la_data_out[23] = 0 Amplifier positive input: gpio_analog[12] when selected Selection: la_data_out[22] = 0

High speed crystal oscillator (Tamas Hubai) Enable: la_data_out[19] Standby: la_data_out[20] Bias: 10uA when selected Selection: la_data_out[47] = 0 Upstream analog power supply: vdda2/vssa2 Upstream digital power supply: vccd2/vssd2 Power supply monitor: io_analog[6] Power supply enable: la_data_out[52] Power supply !enable: la_data_out[53] Oscillator out: io_out[23] Crystal Xin: gpio_analog[14] Crystal Xout: gpio_analog[15]

Bandgap (Christoph Weiser) Enable: none (enable via power supply) Bias: self-biased Trim: la_data_out[9,8,10,7,11,6,12,5,13,4,14,3,15,2,16,1] Upstream digital power supply: vccd2/vssd2 Power supply monitor: io_analog[5] Power supply enable: la_data_out[50] Power supply !enable: la_data_out[51] Bandgap output: gpio_analog[16] when selected Selection: la_data_out[18] = 1

Brownout detector (Robin Tsang) Enable: la_data_out[109] Bias: gpio_noesd[2] (nominally 1.2V) when selected Selection: la_data_out[122] = 0 Bias: 200nA when selected Selection: la_data_out[43] = 0 Trip point select (otrip): la_data_out[112:113,111] Trip point select (vtrip): la_data_out[107:106,108] Force enable RC osc: la_data_out[115] Force disable RC osc: la_data_out[114] Force short oneshot: la_data_out[116] Current source select: la_data_out[110] Upstream analog power supply: vdda1/vssa1 Upstream digital power supply: vccd1/vssd1 Power supply monitor: io_analog[0] Power supply enable: la_data_out[77] Power supply !enable: la_data_out[76] Outb: io_out[0] Dcomp: io_out[1] Vunder: io_out[5] Timed out: la_data_in[116]

Overvoltage detector (Robin Tsang) Enable: la_data_out[100] Bias: gpio_noesd[2] (nominally 1.2V) when selected Selection: la_data_out[122] = 0 Bias: 200nA when selected Selection: la_data_out[42] = 0 Trip point select (otrip): la_data_out[105:102] Current source select: la_data_out[101] Upstream analog power supply: vdda1/vssa1 Upstream digital power supply: vccd1/vssd1 Power supply monitor: io_analog[1] Power supply enable: la_data_out[75] Power supply !enable: la_data_out[74] Ovout: io_out[6]

Power-on-reset (Robin Tsang) Bias: gpio_noesd[2] (nominally 1.2V) when selected Selection: la_data_out[122] = 0 Bias: 200nA when selected Selection: la_data_out[41] = 0 Trip point select (otrip): la_data_out[96:98] Force PDN: la_data_out[94] Force enable RC osc: la_data_out[93] Force disable RC osc: la_data_out[92] Force short oneshot: la_data_out[99] Current source select: la_data_out[95] Upstream analog power supply: vdda1/vssa1 Upstream digital power supply: vccd1/vssd1 Power supply monitor: io_analog[2] Power supply enable: la_data_out[73] Power supply !enable: la_data_out[72] POR: io_out[7] PORb: io_out[9] Osc_clk: io_out[3] Dcomp: io_out[2] Pwup_filt: io_out[4] Startup timed out: la_data_in[120] POR timed out: la_data_io[119]

Low-speed (32kHz) crystal oscillator (Brady Etz) Enable: la_data_out[86] Standby: la_data_out[85] Bias: 50nA when selected Selection: la_data_out[39] = 0 Upstream analog power supply: vdda1/vssa1 Upstream digital power supply: vccd1/vssd1 Power supply monitor: io_analog[3] Power supply enable: la_data_out[69] Power supply !enable: la_data_out[68] Dout: io_out[12] Crystal XIn: gpio_noesd[3] Crystal XOut: gpio_noesd[4]

Overvoltage detector (Lucas Franck & William Orlato) Enable: la_data_out[91] Bias: gpio_noesd[2] (nominally 1.2V) when selected Selection: la_data_out[122] = 1 Trip point select (vtrip): la_data_out[87:90] Upstream analog power supply: vdda1/vssa1 Upstream digital power supply: vccd1/vssd1 Power supply monitor: io_analog[4] Power supply enable: la_data_out[65] Power supply !enable: la_data_out[64] OVout: io_out[13]

Three power FETs are unused but should be kept disabled: Enable: la_data_out[62], la_data_out[67], la_data_out[71] Disable: la_data_out[63], la_data_out[66], la_data_out[70]

These current sources/sinks are multiplexed to analog pins not otherwise being used for projects:

100nA source (test0): gpio_analog[16] when selected Selection: la_data_out[18] = 0

100nA source (test1): gpio_analog[10] when selected Selection: la_data_out[17] = 1

100nA sink (test1): gpio_analog[6] when selected Selection: la_data_out[124] = 1

3.7uA sink (snk_3700): gpio_analog[5] when selected Selection: la_data_out[123] = 1

100nA sink (test0): gpio_analog[0] when selected Selection: la_data_out[118] = 1

Refer to README for this sample project documentation.