Orbit Noise Generator Wireless Board (WiBo)

WiBo102 is a 4.00 x 4.00” printed circuit board (PCB) designed around a Maxim, Inc. MAX2829ETN+D radio transceiver chip. This chip incorporates most of the radio functions except for the reference oscillator, baseband I/Q amps, power amps and antenna switches.

Four antennas (A01-A04) are mounted directly to WiBo102 though provision is made for adding SMA connectors and using off-board antennas if necessary. Two antennas are primarily for transmission (Tx) and two for receiving (Rx). Antenna switching is possible for diversity gain. It is also possible to switch all Tx and Rx signals into a single antenna.

1. PCB

The PCB is a 4.00 x 4.00” FR-4 four-layer controlled impedance stackup board manufactured by Advanced Circuits, Inc.(​http://www.4pcb.com/index.htm). For orientation purposes, reference marks are shown along the top (A-D) and right sides (1-4) of the board in one inch increments.

Looking from the top down, the top copper layer is the component side with all the high-frequency RF transmission lines. The dielectric under this layer is 20 mils thick. The structure of the traces is coplanar waveguide with ground (CPWG). A trace width of 30 mils and gap-to-ground of 18 mils provides a very close match to a 50ohm characteristic impedance.

The next copper layer down is all ground plane. The third layer down is a signal layer with predominately vertical traces surrounded by ground plane. The fourth or bottom layer is another signal layer with predominately horizontal traces.

BiBo’s ADC (analog-to-digital conversion) and DAC (digital-to-analog) conversion comes from an Analog Devices AD9860 MxFE processor. Digital RADIO_IO_x signals come from a Xilinx Spartan 3.

RADIO_IO_1/¾ download programming coefficients to the MAX2829.

RADIO_IO_3/4 are shared with U2 (74HC595), an 8bit serial in parallel out shift register. ​http://www.fairchildsemi.com/ds/MM/MM74HC595.pdf U2 in turn controls five functions, namely, turn on/off of the 2GHz and 5GHz power amps, MAX2829 RXENA and TXENA signals and the MAX2829 shutdown (/SHDN). Meaning of control signals

Assuming the MAX2829 has already been programmed, to enable a TX RF output the user must program a 11001xxx into U2.

NOTE! Do not turn on both the 2GHz and the 5GHz power amps at the same time! ALSO! Do not turn on both the RXENA and TXENA lines (not sure why?).

Connector J3_F and I/O

This is a 40-pin 2mm dual-inline connector which mates BiBo’s control signals, +3.3 VDC power and ground to WiBo102.

WiBo102 function	J3_F function	pin#	pin#	J3_F function	WiBo102 function
hi-speed MAX2829 TXBBQ-	DACB-	2	1	3.3VA
hi-speed MAX2829 TXBBQ+	DACB+	4	3	GND
hi-speed MAX2829 TXBBI-	DACA+	6	5	3.3VA
hi-speed MAX2829 TXBBI+	DACA-	8	7	GND
phase modulation of U23	AUX_DAC_C	10	9	3.3VA
ref osc VCXO frequency adjust	AUX_DAC_B	12	11	GND
PLL speed up monitor	AUX_DAC_A	14	13	3.3VA
½ supply voltage	AUX_ADC_A1	1	15	GND
RSSI from MAX2829	AUX_ADC_A2	18	17	N/C
2GHz power amp detector	AUX_ADC_B1	20	19	3.3VD
5GHz power amp detector	AUX_ADC_B2	22	21	GND
hi-speed MAX2829 RXI+	ADCA+	24	23	3.3VD
hi-speed MAX2829 RXI-	ADCA_	26	25	GND
hi-speed MAX2829 RXQ+	ADCB+	28	27	3.3VD
hi-speed MAX2829 RXQ-	ADCB-	30	29	GND
MAX2829 /CS	RADIO_IO 1	32	31	3.3VD
U2 RCK	RADIO_IO 2	34	33	GND
MAX2829 SCLK and U2 SCK	RADIO_IO 3	36	35	RADIO_IO 8	MAX2829 LD (lock=1=LED on)
MAX2829 DIN and U2 SER	RADIO_IO 4	38	37	RADIO_IO 7	U5 switch(straight=0,cross=1)
U3 switch(straight=0,cross=1)	RADIO_IO 5	40	39	RADIO_IO 6	U4 switch(straight=0,cross=1)

Control Register U2

Note: A is the first bit in, so shift in reverse order

012345678	Function
1xxxxxxxx	turn MAX2829 on (/SHDN)
x1xxxxxxx	turn MAX2829 TX on (TXENA)
xx1xxxxxx	turn MAX2829 RX on (RXENA)
xxx1xxxxx	5G PA: 5GHZ power amp on
xxxx1xxxx	2G PA: 2GHz power amp on
xxxxx1xxx	SPARE 1 output on
xxxxxx1xx	SPARE 2 output on
xxxxxxx1x	SPARE 3 output on
xxxxxxxx1	SPARE 4 output on, 9th bit