Q1:
In the datasheet of the MAX3658, page 7 it is stated "Power-supply bypassing should provide low impedance between VCC and ground for frequencies between 10kHz and 700MHz."
What value do you recommend for "low-impedance"?
A1:
Power supply decoupling would depend on your space constraints. If you can, try to follow the MAX3658 EV Kit data sheet as much as possible. In general, try to use a pi or L type capacitive- inductive filter at the VCC terminal then use more capacitive decoupling as close as possible to the on-chip VCC pin.
In our MAX3658EVKIT design, which uses a pi filter at the VCC terminal (2.2uF, Ferrite Bead, 0.1uF) and decoupling capacitors very close to the chip's VCC pin (2200pF in parallel with 100pF) the impedance at 10kHz is very low (milli-ohm range) and at 700MHz is less than 1 ohm.