Hi all,

our customers has been asking about min. reference input level over various input type at ADF4153.

so recently, this problem is definded two case as below.

also, we got a conversion equation when Vpp is converted by dBm at sinewave .

To conclude, minimum ref input range of square wave is decreased than sine wave as below.

1) where) 51ohm shunt resistor must use at reference input.

1) Sine wave(need input level over -4dBm)

10log(0.4)^2/(0.008*50) = -3.98dBm

2) Square wave(need input level over -1dBm)

10log(0.4)^2/(0.004*50) = -0.97dBm

2) when the CLK is high impedance and waveform is TTL, CMOS or sinewave form. the below spec will be used.

I want to discuss upper condition is right or not? could you please tell me if you have another idea?

I wish to help when you design PLLIC.

Hi,

The datasheet specification says that minimum value of the signal on Reference input is 0.7 Vp-p (peak- to peak) without specifying the shape of the signal.

For both sine wave and square wave, this value is equal to 0.35 Vpk (volts peak) and for 51 ohm load this gives value of 0.7954 dBm for sine wave and 3.806 dBm for square wave .

To easily calculate the units for different signal shape and load value, you might use this online calculator provided by Analog Devices: http://designtools.analog.com/dt/dbconvert/dbconvert.html

Regards

Grzegorz Wawrzola